From 3cb50a4714b6836a1d32e383edc86b3557d861ea Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 23 Jul 2020 18:18:13 +0200
Subject: [PATCH] LibWeb: Rename Element::tag_name() => local_name()

To prepare for fully qualified tag names, let's call this local_name.
Note that we still keep an Element::tag_name() around since that's what
the JS bindings end up calling into for the Element.tagName property.
---
 Libraries/LibWeb/CSS/SelectorEngine.cpp       |   2 +-
 Libraries/LibWeb/DOM/Document.cpp             |   4 +-
 Libraries/LibWeb/DOM/Document.h               |   2 +-
 Libraries/LibWeb/DOM/Element.cpp              |   6 +-
 Libraries/LibWeb/DOM/Element.h                |   7 +-
 Libraries/LibWeb/DOM/HTMLAnchorElement.h      |   4 +-
 Libraries/LibWeb/DOM/HTMLBRElement.h          |   4 +-
 Libraries/LibWeb/DOM/HTMLBlinkElement.h       |   4 +-
 Libraries/LibWeb/DOM/HTMLBodyElement.h        |   4 +-
 Libraries/LibWeb/DOM/HTMLCanvasElement.h      |   4 +-
 Libraries/LibWeb/DOM/HTMLElement.h            |   2 +-
 Libraries/LibWeb/DOM/HTMLFontElement.h        |   4 +-
 Libraries/LibWeb/DOM/HTMLFormElement.h        |   4 +-
 Libraries/LibWeb/DOM/HTMLHRElement.h          |   4 +-
 Libraries/LibWeb/DOM/HTMLHeadElement.h        |   4 +-
 Libraries/LibWeb/DOM/HTMLHeadingElement.h     |   2 +-
 Libraries/LibWeb/DOM/HTMLHtmlElement.h        |   4 +-
 Libraries/LibWeb/DOM/HTMLIFrameElement.h      |   4 +-
 Libraries/LibWeb/DOM/HTMLImageElement.h       |   4 +-
 Libraries/LibWeb/DOM/HTMLInputElement.h       |   4 +-
 Libraries/LibWeb/DOM/HTMLLinkElement.h        |   4 +-
 Libraries/LibWeb/DOM/HTMLObjectElement.h      |   4 +-
 Libraries/LibWeb/DOM/HTMLScriptElement.h      |   4 +-
 Libraries/LibWeb/DOM/HTMLStyleElement.h       |   4 +-
 Libraries/LibWeb/DOM/HTMLTableCellElement.h   |   4 +-
 Libraries/LibWeb/DOM/HTMLTableElement.h       |   4 +-
 Libraries/LibWeb/DOM/HTMLTableRowElement.h    |   4 +-
 Libraries/LibWeb/DOM/HTMLTitleElement.h       |   4 +-
 Libraries/LibWeb/DOMTreeModel.cpp             |   2 +-
 Libraries/LibWeb/Dump.cpp                     |   4 +-
 Libraries/LibWeb/LayoutTreeModel.cpp          |   2 +-
 .../LibWeb/Parser/HTMLDocumentParser.cpp      | 144 +++++++++---------
 .../Parser/ListOfActiveFormattingElements.cpp |   2 +-
 .../LibWeb/Parser/StackOfOpenElements.cpp     |  14 +-
 34 files changed, 140 insertions(+), 137 deletions(-)

diff --git a/Libraries/LibWeb/CSS/SelectorEngine.cpp b/Libraries/LibWeb/CSS/SelectorEngine.cpp
index 654fe6ac95..b080c37edc 100644
--- a/Libraries/LibWeb/CSS/SelectorEngine.cpp
+++ b/Libraries/LibWeb/CSS/SelectorEngine.cpp
@@ -110,7 +110,7 @@ bool matches(const Selector::SimpleSelector& component, const Element& element)
     case Selector::SimpleSelector::Type::Class:
         return element.has_class(component.value);
     case Selector::SimpleSelector::Type::TagName:
-        return component.value == element.tag_name();
+        return component.value == element.local_name();
     default:
         ASSERT_NOT_REACHED();
     }
diff --git a/Libraries/LibWeb/DOM/Document.cpp b/Libraries/LibWeb/DOM/Document.cpp
index feda9d7312..fe0e47ce17 100644
--- a/Libraries/LibWeb/DOM/Document.cpp
+++ b/Libraries/LibWeb/DOM/Document.cpp
@@ -334,11 +334,11 @@ Vector<const Element*> Document::get_elements_by_name(const String& name) const
     return elements;
 }
 
-NonnullRefPtrVector<Element> Document::get_elements_by_tag_name(const String& tag_name) const
+NonnullRefPtrVector<Element> Document::get_elements_by_tag_name(const FlyString& tag_name) const
 {
     NonnullRefPtrVector<Element> elements;
     for_each_in_subtree_of_type<Element>([&](auto& element) {
-        if (element.tag_name() == tag_name)
+        if (element.local_name() == tag_name)
             elements.append(element);
         return IterationDecision::Continue;
     });
diff --git a/Libraries/LibWeb/DOM/Document.h b/Libraries/LibWeb/DOM/Document.h
index a6a2e1d761..ce198415f5 100644
--- a/Libraries/LibWeb/DOM/Document.h
+++ b/Libraries/LibWeb/DOM/Document.h
@@ -124,7 +124,7 @@ public:
     void schedule_style_update();
 
     Vector<const Element*> get_elements_by_name(const String&) const;
-    NonnullRefPtrVector<Element> get_elements_by_tag_name(const String&) const;
+    NonnullRefPtrVector<Element> get_elements_by_tag_name(const FlyString&) const;
     RefPtr<Element> query_selector(const StringView&);
     NonnullRefPtrVector<Element> query_selector_all(const StringView&);
 
diff --git a/Libraries/LibWeb/DOM/Element.cpp b/Libraries/LibWeb/DOM/Element.cpp
index 27e00d63d1..21dc1b0d7b 100644
--- a/Libraries/LibWeb/DOM/Element.cpp
+++ b/Libraries/LibWeb/DOM/Element.cpp
@@ -116,7 +116,7 @@ RefPtr<LayoutNode> Element::create_layout_node(const StyleProperties* parent_sty
     if (display == CSS::Display::None)
         return nullptr;
 
-    if (tag_name() == "noscript" && document().is_scripting_enabled())
+    if (local_name() == "noscript" && document().is_scripting_enabled())
         return nullptr;
 
     if (display == CSS::Display::Block)
@@ -271,13 +271,13 @@ String Element::inner_html() const
         for (auto* child = node.first_child(); child; child = child->next_sibling()) {
             if (child->is_element()) {
                 builder.append('<');
-                builder.append(to<Element>(*child).tag_name());
+                builder.append(to<Element>(*child).local_name());
                 builder.append('>');
 
                 recurse(*child);
 
                 builder.append("</");
-                builder.append(to<Element>(*child).tag_name());
+                builder.append(to<Element>(*child).local_name());
                 builder.append('>');
             }
             if (child->is_text()) {
diff --git a/Libraries/LibWeb/DOM/Element.h b/Libraries/LibWeb/DOM/Element.h
index 1b6ea79f36..b99edfd74e 100644
--- a/Libraries/LibWeb/DOM/Element.h
+++ b/Libraries/LibWeb/DOM/Element.h
@@ -42,11 +42,14 @@ class Element : public ParentNode {
 public:
     using WrapperType = Bindings::ElementWrapper;
 
-    Element(Document&, const FlyString& tag_name);
+    Element(Document&, const FlyString& local_name);
     virtual ~Element() override;
 
     virtual FlyString node_name() const final { return m_tag_name; }
-    const FlyString& tag_name() const { return m_tag_name; }
+    const FlyString& local_name() const { return m_tag_name; }
+
+    // NOTE: This is for the JS bindings
+    const FlyString& tag_name() const { return local_name(); }
 
     bool has_attribute(const FlyString& name) const { return !attribute(name).is_null(); }
     String attribute(const FlyString& name) const;
diff --git a/Libraries/LibWeb/DOM/HTMLAnchorElement.h b/Libraries/LibWeb/DOM/HTMLAnchorElement.h
index d52557b8c3..c7179b8087 100644
--- a/Libraries/LibWeb/DOM/HTMLAnchorElement.h
+++ b/Libraries/LibWeb/DOM/HTMLAnchorElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLAnchorElement : public HTMLElement {
 public:
-    HTMLAnchorElement(Document&, const FlyString& tag_name);
+    HTMLAnchorElement(Document&, const FlyString& local_name);
     virtual ~HTMLAnchorElement() override;
 
     String href() const { return attribute(HTML::AttributeNames::href); }
@@ -42,7 +42,7 @@ public:
 template<>
 inline bool is<HTMLAnchorElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::a;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::a;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLBRElement.h b/Libraries/LibWeb/DOM/HTMLBRElement.h
index 04009f68b7..1c86024df4 100644
--- a/Libraries/LibWeb/DOM/HTMLBRElement.h
+++ b/Libraries/LibWeb/DOM/HTMLBRElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLBRElement final : public HTMLElement {
 public:
-    HTMLBRElement(Document&, const FlyString& tag_name);
+    HTMLBRElement(Document&, const FlyString& local_name);
     virtual ~HTMLBRElement() override;
 
     virtual RefPtr<LayoutNode> create_layout_node(const StyleProperties* parent_style) override;
@@ -41,7 +41,7 @@ public:
 template<>
 inline bool is<HTMLBRElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::br;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::br;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLBlinkElement.h b/Libraries/LibWeb/DOM/HTMLBlinkElement.h
index d9ff921fa4..6696f2cae3 100644
--- a/Libraries/LibWeb/DOM/HTMLBlinkElement.h
+++ b/Libraries/LibWeb/DOM/HTMLBlinkElement.h
@@ -33,7 +33,7 @@ namespace Web {
 
 class HTMLBlinkElement : public HTMLElement {
 public:
-    HTMLBlinkElement(Document&, const FlyString& tag_name);
+    HTMLBlinkElement(Document&, const FlyString& local_name);
     virtual ~HTMLBlinkElement() override;
 
 private:
@@ -45,7 +45,7 @@ private:
 template<>
 inline bool is<HTMLBlinkElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::blink;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::blink;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLBodyElement.h b/Libraries/LibWeb/DOM/HTMLBodyElement.h
index 75a80743dc..bc0688d89e 100644
--- a/Libraries/LibWeb/DOM/HTMLBodyElement.h
+++ b/Libraries/LibWeb/DOM/HTMLBodyElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLBodyElement : public HTMLElement {
 public:
-    HTMLBodyElement(Document&, const FlyString& tag_name);
+    HTMLBodyElement(Document&, const FlyString& local_name);
     virtual ~HTMLBodyElement() override;
 
     virtual void parse_attribute(const FlyString&, const String&) override;
@@ -45,7 +45,7 @@ private:
 template<>
 inline bool is<HTMLBodyElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::body;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::body;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLCanvasElement.h b/Libraries/LibWeb/DOM/HTMLCanvasElement.h
index 41722ec184..dd9e3f41ec 100644
--- a/Libraries/LibWeb/DOM/HTMLCanvasElement.h
+++ b/Libraries/LibWeb/DOM/HTMLCanvasElement.h
@@ -38,7 +38,7 @@ class HTMLCanvasElement : public HTMLElement {
 public:
     using WrapperType = Bindings::HTMLCanvasElementWrapper;
 
-    HTMLCanvasElement(Document&, const FlyString& tag_name);
+    HTMLCanvasElement(Document&, const FlyString& local_name);
     virtual ~HTMLCanvasElement() override;
 
     const Gfx::Bitmap* bitmap() const { return m_bitmap; }
@@ -60,7 +60,7 @@ private:
 template<>
 inline bool is<HTMLCanvasElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::canvas;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::canvas;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLElement.h b/Libraries/LibWeb/DOM/HTMLElement.h
index f3b42191c9..054f7c613e 100644
--- a/Libraries/LibWeb/DOM/HTMLElement.h
+++ b/Libraries/LibWeb/DOM/HTMLElement.h
@@ -34,7 +34,7 @@ class HTMLElement : public Element {
 public:
     using WrapperType = Bindings::HTMLElementWrapper;
 
-    HTMLElement(Document&, const FlyString& tag_name);
+    HTMLElement(Document&, const FlyString& local_name);
     virtual ~HTMLElement() override;
 
     String title() const { return attribute(HTML::AttributeNames::title); }
diff --git a/Libraries/LibWeb/DOM/HTMLFontElement.h b/Libraries/LibWeb/DOM/HTMLFontElement.h
index 4f9484d370..15da127d47 100644
--- a/Libraries/LibWeb/DOM/HTMLFontElement.h
+++ b/Libraries/LibWeb/DOM/HTMLFontElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLFontElement : public HTMLElement {
 public:
-    HTMLFontElement(Document&, const FlyString& tag_name);
+    HTMLFontElement(Document&, const FlyString& local_name);
     virtual ~HTMLFontElement() override;
 
     virtual void apply_presentational_hints(StyleProperties&) const override;
@@ -41,7 +41,7 @@ public:
 template<>
 inline bool is<HTMLFontElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::font;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::font;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLFormElement.h b/Libraries/LibWeb/DOM/HTMLFormElement.h
index db0297e1f2..5986653ea6 100644
--- a/Libraries/LibWeb/DOM/HTMLFormElement.h
+++ b/Libraries/LibWeb/DOM/HTMLFormElement.h
@@ -33,7 +33,7 @@ namespace Web {
 
 class HTMLFormElement : public HTMLElement {
 public:
-    HTMLFormElement(Document&, const FlyString& tag_name);
+    HTMLFormElement(Document&, const FlyString& local_name);
     virtual ~HTMLFormElement() override;
 
     String action() const { return attribute(HTML::AttributeNames::action); }
@@ -45,7 +45,7 @@ public:
 template<>
 inline bool is<HTMLFormElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::form;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::form;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLHRElement.h b/Libraries/LibWeb/DOM/HTMLHRElement.h
index 31c23deae4..3e8f84e71a 100644
--- a/Libraries/LibWeb/DOM/HTMLHRElement.h
+++ b/Libraries/LibWeb/DOM/HTMLHRElement.h
@@ -32,14 +32,14 @@ namespace Web {
 
 class HTMLHRElement : public HTMLElement {
 public:
-    HTMLHRElement(Document&, const FlyString& tag_name);
+    HTMLHRElement(Document&, const FlyString& local_name);
     virtual ~HTMLHRElement() override;
 };
 
 template<>
 inline bool is<HTMLHRElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::hr;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::hr;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLHeadElement.h b/Libraries/LibWeb/DOM/HTMLHeadElement.h
index f20f5ef414..fb4661605e 100644
--- a/Libraries/LibWeb/DOM/HTMLHeadElement.h
+++ b/Libraries/LibWeb/DOM/HTMLHeadElement.h
@@ -32,14 +32,14 @@ namespace Web {
 
 class HTMLHeadElement : public HTMLElement {
 public:
-    HTMLHeadElement(Document&, const FlyString& tag_name);
+    HTMLHeadElement(Document&, const FlyString& local_name);
     virtual ~HTMLHeadElement() override;
 };
 
 template<>
 inline bool is<HTMLHeadElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name().equals_ignoring_case("head");
+    return is<Element>(node) && to<Element>(node).local_name().equals_ignoring_case("head");
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLHeadingElement.h b/Libraries/LibWeb/DOM/HTMLHeadingElement.h
index 06e2e4af58..d2372c14c2 100644
--- a/Libraries/LibWeb/DOM/HTMLHeadingElement.h
+++ b/Libraries/LibWeb/DOM/HTMLHeadingElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLHeadingElement : public HTMLElement {
 public:
-    HTMLHeadingElement(Document&, const FlyString& tag_name);
+    HTMLHeadingElement(Document&, const FlyString& local_name);
     virtual ~HTMLHeadingElement() override;
 };
 
diff --git a/Libraries/LibWeb/DOM/HTMLHtmlElement.h b/Libraries/LibWeb/DOM/HTMLHtmlElement.h
index 814b869f7a..c57815c4cc 100644
--- a/Libraries/LibWeb/DOM/HTMLHtmlElement.h
+++ b/Libraries/LibWeb/DOM/HTMLHtmlElement.h
@@ -32,14 +32,14 @@ namespace Web {
 
 class HTMLHtmlElement : public HTMLElement {
 public:
-    HTMLHtmlElement(Document&, const FlyString& tag_name);
+    HTMLHtmlElement(Document&, const FlyString& local_name);
     virtual ~HTMLHtmlElement() override;
 };
 
 template<>
 inline bool is<HTMLHtmlElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name().equals_ignoring_case("html");
+    return is<Element>(node) && to<Element>(node).local_name().equals_ignoring_case("html");
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLIFrameElement.h b/Libraries/LibWeb/DOM/HTMLIFrameElement.h
index acfd870324..1fe26cc090 100644
--- a/Libraries/LibWeb/DOM/HTMLIFrameElement.h
+++ b/Libraries/LibWeb/DOM/HTMLIFrameElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLIFrameElement final : public HTMLElement {
 public:
-    HTMLIFrameElement(Document&, const FlyString& tag_name);
+    HTMLIFrameElement(Document&, const FlyString& local_name);
     virtual ~HTMLIFrameElement() override;
 
     virtual RefPtr<LayoutNode> create_layout_node(const StyleProperties* parent_style) override;
@@ -54,7 +54,7 @@ private:
 template<>
 inline bool is<HTMLIFrameElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::iframe;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::iframe;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLImageElement.h b/Libraries/LibWeb/DOM/HTMLImageElement.h
index fff36b0359..a7e0d40e68 100644
--- a/Libraries/LibWeb/DOM/HTMLImageElement.h
+++ b/Libraries/LibWeb/DOM/HTMLImageElement.h
@@ -40,7 +40,7 @@ class HTMLImageElement final : public HTMLElement {
 public:
     using WrapperType = Bindings::HTMLImageElementWrapper;
 
-    HTMLImageElement(Document&, const FlyString& tag_name);
+    HTMLImageElement(Document&, const FlyString& local_name);
     virtual ~HTMLImageElement() override;
 
     virtual void parse_attribute(const FlyString& name, const String& value) override;
@@ -63,7 +63,7 @@ private:
 template<>
 inline bool is<HTMLImageElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::img;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::img;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLInputElement.h b/Libraries/LibWeb/DOM/HTMLInputElement.h
index 4a087391b0..a894efa321 100644
--- a/Libraries/LibWeb/DOM/HTMLInputElement.h
+++ b/Libraries/LibWeb/DOM/HTMLInputElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLInputElement : public HTMLElement {
 public:
-    HTMLInputElement(Document&, const FlyString& tag_name);
+    HTMLInputElement(Document&, const FlyString& local_name);
     virtual ~HTMLInputElement() override;
 
     virtual RefPtr<LayoutNode> create_layout_node(const StyleProperties* parent_style) override;
@@ -45,7 +45,7 @@ public:
 template<>
 inline bool is<HTMLInputElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::input;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::input;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLLinkElement.h b/Libraries/LibWeb/DOM/HTMLLinkElement.h
index 07eb119a7b..d6beb03fad 100644
--- a/Libraries/LibWeb/DOM/HTMLLinkElement.h
+++ b/Libraries/LibWeb/DOM/HTMLLinkElement.h
@@ -35,7 +35,7 @@ class HTMLLinkElement final
     : public HTMLElement
     , public ResourceClient {
 public:
-    HTMLLinkElement(Document&, const FlyString& tag_name);
+    HTMLLinkElement(Document&, const FlyString& local_name);
     virtual ~HTMLLinkElement() override;
 
     virtual void inserted_into(Node&) override;
@@ -67,7 +67,7 @@ private:
 template<>
 inline bool is<HTMLLinkElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::link;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::link;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLObjectElement.h b/Libraries/LibWeb/DOM/HTMLObjectElement.h
index 337cb99074..d8caab1b38 100644
--- a/Libraries/LibWeb/DOM/HTMLObjectElement.h
+++ b/Libraries/LibWeb/DOM/HTMLObjectElement.h
@@ -37,7 +37,7 @@ class LayoutDocument;
 
 class HTMLObjectElement final : public HTMLElement {
 public:
-    HTMLObjectElement(Document&, const FlyString& tag_name);
+    HTMLObjectElement(Document&, const FlyString& local_name);
     virtual ~HTMLObjectElement() override;
 
     virtual void parse_attribute(const FlyString& name, const String& value) override;
@@ -55,7 +55,7 @@ private:
 template<>
 inline bool is<HTMLObjectElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::object;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::object;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLScriptElement.h b/Libraries/LibWeb/DOM/HTMLScriptElement.h
index 9d89ecd812..b9fbb57d92 100644
--- a/Libraries/LibWeb/DOM/HTMLScriptElement.h
+++ b/Libraries/LibWeb/DOM/HTMLScriptElement.h
@@ -33,7 +33,7 @@ namespace Web {
 
 class HTMLScriptElement : public HTMLElement {
 public:
-    HTMLScriptElement(Document&, const FlyString& tag_name);
+    HTMLScriptElement(Document&, const FlyString& local_name);
     virtual ~HTMLScriptElement() override;
 
     bool is_non_blocking() const { return m_non_blocking; }
@@ -68,7 +68,7 @@ private:
 template<>
 inline bool is<HTMLScriptElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::script;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::script;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLStyleElement.h b/Libraries/LibWeb/DOM/HTMLStyleElement.h
index f4d6f30c73..efe6c89ecb 100644
--- a/Libraries/LibWeb/DOM/HTMLStyleElement.h
+++ b/Libraries/LibWeb/DOM/HTMLStyleElement.h
@@ -34,7 +34,7 @@ class StyleSheet;
 
 class HTMLStyleElement : public HTMLElement {
 public:
-    HTMLStyleElement(Document&, const FlyString& tag_name);
+    HTMLStyleElement(Document&, const FlyString& local_name);
     virtual ~HTMLStyleElement() override;
 
     virtual void children_changed() override;
@@ -47,7 +47,7 @@ private:
 template<>
 inline bool is<HTMLStyleElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::style;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::style;
 }
 
 
diff --git a/Libraries/LibWeb/DOM/HTMLTableCellElement.h b/Libraries/LibWeb/DOM/HTMLTableCellElement.h
index 15de7c51b0..8d1f2d90f6 100644
--- a/Libraries/LibWeb/DOM/HTMLTableCellElement.h
+++ b/Libraries/LibWeb/DOM/HTMLTableCellElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLTableCellElement final : public HTMLElement {
 public:
-    HTMLTableCellElement(Document&, const FlyString& tag_name);
+    HTMLTableCellElement(Document&, const FlyString& local_name);
     virtual ~HTMLTableCellElement() override;
 
 private:
@@ -42,7 +42,7 @@ private:
 template<>
 inline bool is<HTMLTableCellElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th);
+    return is<Element>(node) && to<Element>(node).local_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th);
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLTableElement.h b/Libraries/LibWeb/DOM/HTMLTableElement.h
index a6b8689a85..777a6f96f5 100644
--- a/Libraries/LibWeb/DOM/HTMLTableElement.h
+++ b/Libraries/LibWeb/DOM/HTMLTableElement.h
@@ -32,7 +32,7 @@ namespace Web {
 
 class HTMLTableElement final : public HTMLElement {
 public:
-    HTMLTableElement(Document&, const FlyString& tag_name);
+    HTMLTableElement(Document&, const FlyString& local_name);
     virtual ~HTMLTableElement() override;
 
 private:
@@ -42,7 +42,7 @@ private:
 template<>
 inline bool is<HTMLTableElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::table;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::table;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLTableRowElement.h b/Libraries/LibWeb/DOM/HTMLTableRowElement.h
index 6e48579914..3940e1b02d 100644
--- a/Libraries/LibWeb/DOM/HTMLTableRowElement.h
+++ b/Libraries/LibWeb/DOM/HTMLTableRowElement.h
@@ -32,14 +32,14 @@ namespace Web {
 
 class HTMLTableRowElement : public HTMLElement {
 public:
-    HTMLTableRowElement(Document&, const FlyString& tag_name);
+    HTMLTableRowElement(Document&, const FlyString& local_name);
     virtual ~HTMLTableRowElement() override;
 };
 
 template<>
 inline bool is<HTMLTableRowElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name() == HTML::TagNames::tr;
+    return is<Element>(node) && to<Element>(node).local_name() == HTML::TagNames::tr;
 }
 
 }
diff --git a/Libraries/LibWeb/DOM/HTMLTitleElement.h b/Libraries/LibWeb/DOM/HTMLTitleElement.h
index d769f26b65..b162d24341 100644
--- a/Libraries/LibWeb/DOM/HTMLTitleElement.h
+++ b/Libraries/LibWeb/DOM/HTMLTitleElement.h
@@ -32,14 +32,14 @@ namespace Web {
 
 class HTMLTitleElement : public HTMLElement {
 public:
-    HTMLTitleElement(Document&, const FlyString& tag_name);
+    HTMLTitleElement(Document&, const FlyString& local_name);
     virtual ~HTMLTitleElement() override;
 };
 
 template<>
 inline bool is<HTMLTitleElement>(const Node& node)
 {
-    return is<Element>(node) && to<Element>(node).tag_name().equals_ignoring_case("title");
+    return is<Element>(node) && to<Element>(node).local_name().equals_ignoring_case("title");
 }
 
 }
diff --git a/Libraries/LibWeb/DOMTreeModel.cpp b/Libraries/LibWeb/DOMTreeModel.cpp
index 1b7030d4fc..c87f48f7c8 100644
--- a/Libraries/LibWeb/DOMTreeModel.cpp
+++ b/Libraries/LibWeb/DOMTreeModel.cpp
@@ -134,7 +134,7 @@ GUI::Variant DOMTreeModel::data(const GUI::ModelIndex& index, Role role) const
         auto& element = to<Element>(node);
         StringBuilder builder;
         builder.append('<');
-        builder.append(element.tag_name());
+        builder.append(element.local_name());
         element.for_each_attribute([&](auto& name, auto& value) {
             builder.append(' ');
             builder.append(name);
diff --git a/Libraries/LibWeb/Dump.cpp b/Libraries/LibWeb/Dump.cpp
index ce10f2a68b..1225027e50 100644
--- a/Libraries/LibWeb/Dump.cpp
+++ b/Libraries/LibWeb/Dump.cpp
@@ -51,7 +51,7 @@ void dump_tree(const Node& node)
     if (is<Document>(node)) {
         dbgprintf("*Document*\n");
     } else if (is<Element>(node)) {
-        dbgprintf("<%s", to<Element>(node).tag_name().characters());
+        dbgprintf("<%s", to<Element>(node).local_name().characters());
         to<Element>(node).for_each_attribute([](auto& name, auto& value) {
             dbgprintf(" %s=%s", name.characters(), value.characters());
         });
@@ -88,7 +88,7 @@ void dump_tree(const LayoutNode& layout_node)
     else if (is<Document>(layout_node.node()))
         tag_name = "#document";
     else if (is<Element>(layout_node.node()))
-        tag_name = to<Element>(*layout_node.node()).tag_name();
+        tag_name = to<Element>(*layout_node.node()).local_name();
     else
         tag_name = "???";
 
diff --git a/Libraries/LibWeb/LayoutTreeModel.cpp b/Libraries/LibWeb/LayoutTreeModel.cpp
index 87dcfb4c30..6a3444d225 100644
--- a/Libraries/LibWeb/LayoutTreeModel.cpp
+++ b/Libraries/LibWeb/LayoutTreeModel.cpp
@@ -138,7 +138,7 @@ GUI::Variant LayoutTreeModel::data(const GUI::ModelIndex& index, Role role) cons
         } else {
             auto& element = to<Element>(*node.node());
             builder.append('<');
-            builder.append(element.tag_name());
+            builder.append(element.local_name());
             element.for_each_attribute([&](auto& name, auto& value) {
                 builder.append(' ');
                 builder.append(name);
diff --git a/Libraries/LibWeb/Parser/HTMLDocumentParser.cpp b/Libraries/LibWeb/Parser/HTMLDocumentParser.cpp
index 9099f4e7d6..83df56146b 100644
--- a/Libraries/LibWeb/Parser/HTMLDocumentParser.cpp
+++ b/Libraries/LibWeb/Parser/HTMLDocumentParser.cpp
@@ -379,7 +379,7 @@ Element& HTMLDocumentParser::node_before_current_node()
 HTMLDocumentParser::AdjustedInsertionLocation HTMLDocumentParser::find_appropriate_place_for_inserting_node()
 {
     auto& target = current_node();
-    if (m_foster_parenting && target.tag_name().is_one_of(HTML::TagNames::table, HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::tr)) {
+    if (m_foster_parenting && target.local_name().is_one_of(HTML::TagNames::table, HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::tr)) {
         // FIXME: There's a bunch of steps for <template> elements here.
         auto last_table = m_stack_of_open_elements.last_element_with_tag_name(HTML::TagNames::table);
         if (!last_table) {
@@ -558,7 +558,7 @@ void HTMLDocumentParser::handle_in_head(HTMLToken& token)
 
     if (token.is_end_tag() && token.tag_name() == HTML::TagNames::template_) {
         // FIXME: Support this properly
-        ASSERT(current_node().tag_name() == HTML::TagNames::template_);
+        ASSERT(current_node().local_name() == HTML::TagNames::template_);
         m_stack_of_open_elements.pop();
         return;
     }
@@ -729,14 +729,14 @@ AnythingElse:
 
 void HTMLDocumentParser::generate_implied_end_tags(const FlyString& exception)
 {
-    while (current_node().tag_name() != exception && current_node().tag_name().is_one_of(HTML::TagNames::dd, HTML::TagNames::dt, HTML::TagNames::li, HTML::TagNames::optgroup, HTML::TagNames::option, HTML::TagNames::p, HTML::TagNames::rb, HTML::TagNames::rp, HTML::TagNames::rt, HTML::TagNames::rtc))
+    while (current_node().local_name() != exception && current_node().local_name().is_one_of(HTML::TagNames::dd, HTML::TagNames::dt, HTML::TagNames::li, HTML::TagNames::optgroup, HTML::TagNames::option, HTML::TagNames::p, HTML::TagNames::rb, HTML::TagNames::rp, HTML::TagNames::rt, HTML::TagNames::rtc))
         m_stack_of_open_elements.pop();
 }
 
 void HTMLDocumentParser::close_a_p_element()
 {
     generate_implied_end_tags(HTML::TagNames::p);
-    if (current_node().tag_name() != HTML::TagNames::p) {
+    if (current_node().local_name() != HTML::TagNames::p) {
         PARSE_ERROR();
     }
     m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::p);
@@ -844,7 +844,7 @@ Advance:
 
 Create:
     // FIXME: Hold on to the real token!
-    auto new_element = insert_html_element(HTMLToken::make_start_tag(entry->tag_name()));
+    auto new_element = insert_html_element(HTMLToken::make_start_tag(entry->local_name()));
 
     m_list_of_active_formatting_elements.entries().at(index).element = *new_element;
 
@@ -859,7 +859,7 @@ HTMLDocumentParser::AdoptionAgencyAlgorithmOutcome HTMLDocumentParser::run_the_a
     // If the current node is an HTML element whose tag name is subject,
     // and the current node is not in the list of active formatting elements,
     // then pop the current node off the stack of open elements, and return.
-    if (current_node().tag_name() == subject && !m_list_of_active_formatting_elements.contains(current_node())) {
+    if (current_node().local_name() == subject && !m_list_of_active_formatting_elements.contains(current_node())) {
         m_stack_of_open_elements.pop();
         return AdoptionAgencyAlgorithmOutcome::DoNothing;
     }
@@ -1047,7 +1047,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
     if (token.is_start_tag() && token.tag_name() == HTML::TagNames::body) {
         PARSE_ERROR();
         if (m_stack_of_open_elements.elements().size() == 1
-            || m_stack_of_open_elements.elements().at(1).tag_name() != HTML::TagNames::body
+            || m_stack_of_open_elements.elements().at(1).local_name() != HTML::TagNames::body
             || m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
             ASSERT(m_parsing_fragment);
             return;
@@ -1066,7 +1066,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         PARSE_ERROR();
 
         if (m_stack_of_open_elements.elements().size() == 1
-            || m_stack_of_open_elements.elements().at(1).tag_name() != HTML::TagNames::body) {
+            || m_stack_of_open_elements.elements().at(1).local_name() != HTML::TagNames::body) {
             ASSERT(m_parsing_fragment);
             return;
         }
@@ -1098,7 +1098,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         }
 
         for (auto& node : m_stack_of_open_elements.elements()) {
-            if (!node.tag_name().is_one_of(HTML::TagNames::dd, HTML::TagNames::dt, HTML::TagNames::li, HTML::TagNames::optgroup, HTML::TagNames::option, HTML::TagNames::p, HTML::TagNames::rb, HTML::TagNames::rp, HTML::TagNames::rt, HTML::TagNames::rtc, HTML::TagNames::tbody, HTML::TagNames::td, HTML::TagNames::tfoot, HTML::TagNames::th, HTML::TagNames::thead, HTML::TagNames::tr, HTML::TagNames::body, HTML::TagNames::html)) {
+            if (!node.local_name().is_one_of(HTML::TagNames::dd, HTML::TagNames::dt, HTML::TagNames::li, HTML::TagNames::optgroup, HTML::TagNames::option, HTML::TagNames::p, HTML::TagNames::rb, HTML::TagNames::rp, HTML::TagNames::rt, HTML::TagNames::rtc, HTML::TagNames::tbody, HTML::TagNames::td, HTML::TagNames::tfoot, HTML::TagNames::th, HTML::TagNames::thead, HTML::TagNames::tr, HTML::TagNames::body, HTML::TagNames::html)) {
                 PARSE_ERROR();
                 break;
             }
@@ -1115,7 +1115,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         }
 
         for (auto& node : m_stack_of_open_elements.elements()) {
-            if (!node.tag_name().is_one_of(HTML::TagNames::dd, HTML::TagNames::dt, HTML::TagNames::li, HTML::TagNames::optgroup, HTML::TagNames::option, HTML::TagNames::p, HTML::TagNames::rb, HTML::TagNames::rp, HTML::TagNames::rt, HTML::TagNames::rtc, HTML::TagNames::tbody, HTML::TagNames::td, HTML::TagNames::tfoot, HTML::TagNames::th, HTML::TagNames::thead, HTML::TagNames::tr, HTML::TagNames::body, HTML::TagNames::html)) {
+            if (!node.local_name().is_one_of(HTML::TagNames::dd, HTML::TagNames::dt, HTML::TagNames::li, HTML::TagNames::optgroup, HTML::TagNames::option, HTML::TagNames::p, HTML::TagNames::rb, HTML::TagNames::rp, HTML::TagNames::rt, HTML::TagNames::rtc, HTML::TagNames::tbody, HTML::TagNames::td, HTML::TagNames::tfoot, HTML::TagNames::th, HTML::TagNames::thead, HTML::TagNames::tr, HTML::TagNames::body, HTML::TagNames::html)) {
                 PARSE_ERROR();
                 break;
             }
@@ -1136,7 +1136,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
     if (token.is_start_tag() && token.tag_name().is_one_of(HTML::TagNames::h1, HTML::TagNames::h2, HTML::TagNames::h3, HTML::TagNames::h4, HTML::TagNames::h5, HTML::TagNames::h6)) {
         if (m_stack_of_open_elements.has_in_button_scope(HTML::TagNames::p))
             close_a_p_element();
-        if (current_node().tag_name().is_one_of(HTML::TagNames::h1, HTML::TagNames::h2, HTML::TagNames::h3, HTML::TagNames::h4, HTML::TagNames::h5, HTML::TagNames::h6)) {
+        if (current_node().local_name().is_one_of(HTML::TagNames::h1, HTML::TagNames::h2, HTML::TagNames::h3, HTML::TagNames::h4, HTML::TagNames::h5, HTML::TagNames::h6)) {
             PARSE_ERROR();
             m_stack_of_open_elements.pop();
         }
@@ -1183,16 +1183,16 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         for (ssize_t i = m_stack_of_open_elements.elements().size() - 1; i >= 0; --i) {
             RefPtr<Element> node = m_stack_of_open_elements.elements()[i];
 
-            if (node->tag_name() == HTML::TagNames::li) {
+            if (node->local_name() == HTML::TagNames::li) {
                 generate_implied_end_tags(HTML::TagNames::li);
-                if (current_node().tag_name() != HTML::TagNames::li) {
+                if (current_node().local_name() != HTML::TagNames::li) {
                     PARSE_ERROR();
                 }
                 m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::li);
                 break;
             }
 
-            if (is_special_tag(node->tag_name()) && !node->tag_name().is_one_of(HTML::TagNames::address, HTML::TagNames::div, HTML::TagNames::p))
+            if (is_special_tag(node->local_name()) && !node->local_name().is_one_of(HTML::TagNames::address, HTML::TagNames::div, HTML::TagNames::p))
                 break;
         }
 
@@ -1207,23 +1207,23 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         m_frameset_ok = false;
         for (ssize_t i = m_stack_of_open_elements.elements().size() - 1; i >= 0; --i) {
             RefPtr<Element> node = m_stack_of_open_elements.elements()[i];
-            if (node->tag_name() == HTML::TagNames::dd) {
+            if (node->local_name() == HTML::TagNames::dd) {
                 generate_implied_end_tags(HTML::TagNames::dd);
-                if (current_node().tag_name() != HTML::TagNames::dd) {
+                if (current_node().local_name() != HTML::TagNames::dd) {
                     PARSE_ERROR();
                 }
                 m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::dd);
                 break;
             }
-            if (node->tag_name() == HTML::TagNames::dt) {
+            if (node->local_name() == HTML::TagNames::dt) {
                 generate_implied_end_tags(HTML::TagNames::dt);
-                if (current_node().tag_name() != HTML::TagNames::dt) {
+                if (current_node().local_name() != HTML::TagNames::dt) {
                     PARSE_ERROR();
                 }
                 m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::dt);
                 break;
             }
-            if (is_special_tag(node->tag_name()) && !node->tag_name().is_one_of(HTML::TagNames::address, HTML::TagNames::div, HTML::TagNames::p))
+            if (is_special_tag(node->local_name()) && !node->local_name().is_one_of(HTML::TagNames::address, HTML::TagNames::div, HTML::TagNames::p))
                 break;
         }
         if (m_stack_of_open_elements.has_in_button_scope(HTML::TagNames::p))
@@ -1260,7 +1260,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
 
         generate_implied_end_tags();
 
-        if (current_node().tag_name() != token.tag_name()) {
+        if (current_node().local_name() != token.tag_name()) {
             PARSE_ERROR();
         }
 
@@ -1287,7 +1287,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
                 return;
             }
             generate_implied_end_tags();
-            if (current_node().tag_name() != HTML::TagNames::form) {
+            if (current_node().local_name() != HTML::TagNames::form) {
                 PARSE_ERROR();
             }
             m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::form);
@@ -1310,9 +1310,9 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
             return;
         }
         generate_implied_end_tags(HTML::TagNames::li);
-        if (current_node().tag_name() != HTML::TagNames::li) {
+        if (current_node().local_name() != HTML::TagNames::li) {
             PARSE_ERROR();
-            dbg() << "Expected <li> current node, but had <" << current_node().tag_name() << ">";
+            dbg() << "Expected <li> current node, but had <" << current_node().local_name() << ">";
         }
         m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::li);
         return;
@@ -1324,7 +1324,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
             return;
         }
         generate_implied_end_tags(token.tag_name());
-        if (current_node().tag_name() != token.tag_name()) {
+        if (current_node().local_name() != token.tag_name()) {
             PARSE_ERROR();
         }
         m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(token.tag_name());
@@ -1343,13 +1343,13 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         }
 
         generate_implied_end_tags();
-        if (current_node().tag_name() != token.tag_name()) {
+        if (current_node().local_name() != token.tag_name()) {
             PARSE_ERROR();
         }
 
         for (;;) {
             auto popped_element = m_stack_of_open_elements.pop();
-            if (popped_element->tag_name().is_one_of(HTML::TagNames::h1, HTML::TagNames::h2, HTML::TagNames::h3, HTML::TagNames::h4, HTML::TagNames::h5, HTML::TagNames::h6))
+            if (popped_element->local_name().is_one_of(HTML::TagNames::h1, HTML::TagNames::h2, HTML::TagNames::h3, HTML::TagNames::h4, HTML::TagNames::h5, HTML::TagNames::h6))
                 break;
         }
         return;
@@ -1411,7 +1411,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         }
 
         generate_implied_end_tags();
-        if (current_node().tag_name() != token.tag_name()) {
+        if (current_node().local_name() != token.tag_name()) {
             PARSE_ERROR();
         }
         m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(token.tag_name());
@@ -1546,7 +1546,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
     }
 
     if (token.is_start_tag() && token.tag_name().is_one_of(HTML::TagNames::optgroup, HTML::TagNames::option)) {
-        if (current_node().tag_name() == HTML::TagNames::option)
+        if (current_node().local_name() == HTML::TagNames::option)
             m_stack_of_open_elements.pop();
         reconstruct_the_active_formatting_elements();
         insert_html_element(token);
@@ -1557,7 +1557,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         if (m_stack_of_open_elements.has_in_scope(HTML::TagNames::ruby))
             generate_implied_end_tags();
 
-        if (current_node().tag_name() != HTML::TagNames::ruby)
+        if (current_node().local_name() != HTML::TagNames::ruby)
             PARSE_ERROR();
 
         insert_html_element(token);
@@ -1568,7 +1568,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         if (m_stack_of_open_elements.has_in_scope(HTML::TagNames::ruby))
             generate_implied_end_tags(HTML::TagNames::rtc);
 
-        if (current_node().tag_name() != HTML::TagNames::rtc || current_node().tag_name() != HTML::TagNames::ruby)
+        if (current_node().local_name() != HTML::TagNames::rtc || current_node().local_name() != HTML::TagNames::ruby)
             PARSE_ERROR();
 
         insert_html_element(token);
@@ -1624,7 +1624,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
         RefPtr<Element> node;
         for (ssize_t i = m_stack_of_open_elements.elements().size() - 1; i >= 0; --i) {
             node = m_stack_of_open_elements.elements()[i];
-            if (node->tag_name() == token.tag_name()) {
+            if (node->local_name() == token.tag_name()) {
                 generate_implied_end_tags(token.tag_name());
                 if (node != current_node()) {
                     PARSE_ERROR();
@@ -1635,7 +1635,7 @@ void HTMLDocumentParser::handle_in_body(HTMLToken& token)
                 m_stack_of_open_elements.pop();
                 break;
             }
-            if (is_special_tag(node->tag_name())) {
+            if (is_special_tag(node->local_name())) {
                 PARSE_ERROR();
                 return;
             }
@@ -1749,7 +1749,7 @@ void HTMLDocumentParser::handle_text(HTMLToken& token)
     }
     if (token.is_end_of_file()) {
         PARSE_ERROR();
-        if (current_node().tag_name() == HTML::TagNames::script)
+        if (current_node().local_name() == HTML::TagNames::script)
             to<HTMLScriptElement>(current_node()).set_already_started({}, true);
         m_stack_of_open_elements.pop();
         m_insertion_mode = m_original_insertion_mode;
@@ -1825,28 +1825,28 @@ void HTMLDocumentParser::handle_text(HTMLToken& token)
 
 void HTMLDocumentParser::clear_the_stack_back_to_a_table_context()
 {
-    while (!current_node().tag_name().is_one_of(HTML::TagNames::table, HTML::TagNames::template_, HTML::TagNames::html))
+    while (!current_node().local_name().is_one_of(HTML::TagNames::table, HTML::TagNames::template_, HTML::TagNames::html))
         m_stack_of_open_elements.pop();
 
-    if (current_node().tag_name() == HTML::TagNames::html)
+    if (current_node().local_name() == HTML::TagNames::html)
         ASSERT(m_parsing_fragment);
 }
 
 void HTMLDocumentParser::clear_the_stack_back_to_a_table_row_context()
 {
-    while (!current_node().tag_name().is_one_of(HTML::TagNames::tr, HTML::TagNames::template_, HTML::TagNames::html))
+    while (!current_node().local_name().is_one_of(HTML::TagNames::tr, HTML::TagNames::template_, HTML::TagNames::html))
         m_stack_of_open_elements.pop();
 
-    if (current_node().tag_name() == HTML::TagNames::html)
+    if (current_node().local_name() == HTML::TagNames::html)
         ASSERT(m_parsing_fragment);
 }
 
 void HTMLDocumentParser::clear_the_stack_back_to_a_table_body_context()
 {
-    while (!current_node().tag_name().is_one_of(HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::template_, HTML::TagNames::html))
+    while (!current_node().local_name().is_one_of(HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::template_, HTML::TagNames::html))
         m_stack_of_open_elements.pop();
 
-    if (current_node().tag_name() == HTML::TagNames::html)
+    if (current_node().local_name() == HTML::TagNames::html)
         ASSERT(m_parsing_fragment);
 }
 
@@ -1910,10 +1910,10 @@ void HTMLDocumentParser::handle_in_row(HTMLToken& token)
 void HTMLDocumentParser::close_the_cell()
 {
     generate_implied_end_tags();
-    if (!current_node().tag_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th)) {
+    if (!current_node().local_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th)) {
         PARSE_ERROR();
     }
-    while (!current_node().tag_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th))
+    while (!current_node().local_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th))
         m_stack_of_open_elements.pop();
     m_stack_of_open_elements.pop();
     m_list_of_active_formatting_elements.clear_up_to_the_last_marker();
@@ -1929,7 +1929,7 @@ void HTMLDocumentParser::handle_in_cell(HTMLToken& token)
         }
         generate_implied_end_tags();
 
-        if (current_node().tag_name() != token.tag_name()) {
+        if (current_node().local_name() != token.tag_name()) {
             PARSE_ERROR();
         }
 
@@ -2057,7 +2057,7 @@ void HTMLDocumentParser::handle_in_table_body(HTMLToken& token)
 
 void HTMLDocumentParser::handle_in_table(HTMLToken& token)
 {
-    if (token.is_character() && current_node().tag_name().is_one_of(HTML::TagNames::table, HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::tr)) {
+    if (token.is_character() && current_node().local_name().is_one_of(HTML::TagNames::table, HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::tr)) {
         m_pending_table_character_tokens.clear();
         m_original_insertion_mode = m_insertion_mode;
         m_insertion_mode = InsertionMode::InTableText;
@@ -2228,7 +2228,7 @@ void HTMLDocumentParser::handle_in_select(HTMLToken& token)
     }
 
     if (token.is_start_tag() && token.tag_name() == HTML::TagNames::option) {
-        if (current_node().tag_name() == HTML::TagNames::option) {
+        if (current_node().local_name() == HTML::TagNames::option) {
             m_stack_of_open_elements.pop();
         }
         insert_html_element(token);
@@ -2236,10 +2236,10 @@ void HTMLDocumentParser::handle_in_select(HTMLToken& token)
     }
 
     if (token.is_start_tag() && token.tag_name() == HTML::TagNames::optgroup) {
-        if (current_node().tag_name() == HTML::TagNames::option) {
+        if (current_node().local_name() == HTML::TagNames::option) {
             m_stack_of_open_elements.pop();
         }
-        if (current_node().tag_name() == HTML::TagNames::optgroup) {
+        if (current_node().local_name() == HTML::TagNames::optgroup) {
             m_stack_of_open_elements.pop();
         }
         insert_html_element(token);
@@ -2247,10 +2247,10 @@ void HTMLDocumentParser::handle_in_select(HTMLToken& token)
     }
 
     if (token.is_end_tag() && token.tag_name() == HTML::TagNames::optgroup) {
-        if (current_node().tag_name() == HTML::TagNames::option && node_before_current_node().tag_name() == HTML::TagNames::optgroup)
+        if (current_node().local_name() == HTML::TagNames::option && node_before_current_node().local_name() == HTML::TagNames::optgroup)
             m_stack_of_open_elements.pop();
 
-        if (current_node().tag_name() == HTML::TagNames::optgroup) {
+        if (current_node().local_name() == HTML::TagNames::optgroup) {
             m_stack_of_open_elements.pop();
         } else {
             PARSE_ERROR();
@@ -2260,7 +2260,7 @@ void HTMLDocumentParser::handle_in_select(HTMLToken& token)
     }
 
     if (token.is_end_tag() && token.tag_name() == HTML::TagNames::option) {
-        if (current_node().tag_name() == HTML::TagNames::option) {
+        if (current_node().local_name() == HTML::TagNames::option) {
             m_stack_of_open_elements.pop();
         } else {
             PARSE_ERROR();
@@ -2336,7 +2336,7 @@ void HTMLDocumentParser::handle_in_caption(HTMLToken& token)
 
         generate_implied_end_tags();
 
-        if (current_node().tag_name() != HTML::TagNames::caption)
+        if (current_node().local_name() != HTML::TagNames::caption)
             PARSE_ERROR();
 
         m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::caption);
@@ -2356,7 +2356,7 @@ void HTMLDocumentParser::handle_in_caption(HTMLToken& token)
 
         generate_implied_end_tags();
 
-        if (current_node().tag_name() != HTML::TagNames::caption)
+        if (current_node().local_name() != HTML::TagNames::caption)
             PARSE_ERROR();
 
         m_stack_of_open_elements.pop_until_an_element_with_tag_name_has_been_popped(HTML::TagNames::caption);
@@ -2405,7 +2405,7 @@ void HTMLDocumentParser::handle_in_column_group(HTMLToken& token)
     }
 
     if (token.is_end_tag() && token.tag_name() == HTML::TagNames::colgroup) {
-        if (current_node().tag_name() != HTML::TagNames::colgroup) {
+        if (current_node().local_name() != HTML::TagNames::colgroup) {
             PARSE_ERROR();
             return;
         }
@@ -2430,7 +2430,7 @@ void HTMLDocumentParser::handle_in_column_group(HTMLToken& token)
         return;
     }
 
-    if (current_node().tag_name() != HTML::TagNames::colgroup) {
+    if (current_node().local_name() != HTML::TagNames::colgroup) {
         PARSE_ERROR();
         return;
     }
@@ -2550,7 +2550,7 @@ void HTMLDocumentParser::handle_in_frameset(HTMLToken& token)
 
         m_stack_of_open_elements.pop();
 
-        if (!m_parsing_fragment && current_node().tag_name() != HTML::TagNames::frameset) {
+        if (!m_parsing_fragment && current_node().local_name() != HTML::TagNames::frameset) {
             m_insertion_mode = InsertionMode::AfterFrameset;
         }
         return;
@@ -2656,61 +2656,61 @@ void HTMLDocumentParser::reset_the_insertion_mode_appropriately()
             node = m_stack_of_open_elements.elements().at(i);
         }
 
-        if (node->tag_name() == HTML::TagNames::select) {
+        if (node->local_name() == HTML::TagNames::select) {
             TODO();
         }
 
-        if (!last && node->tag_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th)) {
+        if (!last && node->local_name().is_one_of(HTML::TagNames::td, HTML::TagNames::th)) {
             m_insertion_mode = InsertionMode::InCell;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::tr) {
+        if (node->local_name() == HTML::TagNames::tr) {
             m_insertion_mode = InsertionMode::InRow;
             return;
         }
 
-        if (node->tag_name().is_one_of(HTML::TagNames::tbody, HTML::TagNames::thead, HTML::TagNames::tfoot)) {
+        if (node->local_name().is_one_of(HTML::TagNames::tbody, HTML::TagNames::thead, HTML::TagNames::tfoot)) {
             m_insertion_mode = InsertionMode::InTableBody;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::caption) {
+        if (node->local_name() == HTML::TagNames::caption) {
             m_insertion_mode = InsertionMode::InCaption;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::colgroup) {
+        if (node->local_name() == HTML::TagNames::colgroup) {
             m_insertion_mode = InsertionMode::InColumnGroup;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::table) {
+        if (node->local_name() == HTML::TagNames::table) {
             m_insertion_mode = InsertionMode::InTable;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::template_) {
+        if (node->local_name() == HTML::TagNames::template_) {
             TODO();
         }
 
-        if (!last && node->tag_name() == HTML::TagNames::head) {
+        if (!last && node->local_name() == HTML::TagNames::head) {
             m_insertion_mode = InsertionMode::InHead;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::body) {
+        if (node->local_name() == HTML::TagNames::body) {
             m_insertion_mode = InsertionMode::InBody;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::frameset) {
+        if (node->local_name() == HTML::TagNames::frameset) {
             ASSERT(m_parsing_fragment);
             m_insertion_mode = InsertionMode::InFrameset;
             return;
         }
 
-        if (node->tag_name() == HTML::TagNames::html) {
+        if (node->local_name() == HTML::TagNames::html) {
             if (!m_head_element) {
                 ASSERT(m_parsing_fragment);
                 m_insertion_mode = InsertionMode::BeforeHead;
@@ -2750,16 +2750,16 @@ NonnullRefPtrVector<Node> HTMLDocumentParser::parse_html_fragment(Element& conte
     parser.m_parsing_fragment = true;
     parser.document().set_quirks_mode(context_element.document().mode());
 
-    if (context_element.tag_name().is_one_of(HTML::TagNames::title, HTML::TagNames::textarea)) {
+    if (context_element.local_name().is_one_of(HTML::TagNames::title, HTML::TagNames::textarea)) {
         parser.m_tokenizer.switch_to({}, HTMLTokenizer::State::RCDATA);
-    } else if (context_element.tag_name().is_one_of(HTML::TagNames::style, HTML::TagNames::xmp, HTML::TagNames::iframe, HTML::TagNames::noembed, HTML::TagNames::noframes)) {
+    } else if (context_element.local_name().is_one_of(HTML::TagNames::style, HTML::TagNames::xmp, HTML::TagNames::iframe, HTML::TagNames::noembed, HTML::TagNames::noframes)) {
         parser.m_tokenizer.switch_to({}, HTMLTokenizer::State::RAWTEXT);
-    } else if (context_element.tag_name().is_one_of(HTML::TagNames::script)) {
+    } else if (context_element.local_name().is_one_of(HTML::TagNames::script)) {
         parser.m_tokenizer.switch_to({}, HTMLTokenizer::State::ScriptData);
-    } else if (context_element.tag_name().is_one_of(HTML::TagNames::noscript)) {
+    } else if (context_element.local_name().is_one_of(HTML::TagNames::noscript)) {
         if (context_element.document().is_scripting_enabled())
             parser.m_tokenizer.switch_to({}, HTMLTokenizer::State::RAWTEXT);
-    } else if (context_element.tag_name().is_one_of(HTML::TagNames::plaintext)) {
+    } else if (context_element.local_name().is_one_of(HTML::TagNames::plaintext)) {
         parser.m_tokenizer.switch_to({}, HTMLTokenizer::State::PLAINTEXT);
     }
 
@@ -2767,7 +2767,7 @@ NonnullRefPtrVector<Node> HTMLDocumentParser::parse_html_fragment(Element& conte
     parser.document().append_child(root);
     parser.m_stack_of_open_elements.push(root);
 
-    if (context_element.tag_name() == HTML::TagNames::template_) {
+    if (context_element.local_name() == HTML::TagNames::template_) {
         TODO();
     }
 
diff --git a/Libraries/LibWeb/Parser/ListOfActiveFormattingElements.cpp b/Libraries/LibWeb/Parser/ListOfActiveFormattingElements.cpp
index 3a52bd6757..6ec79cbae9 100644
--- a/Libraries/LibWeb/Parser/ListOfActiveFormattingElements.cpp
+++ b/Libraries/LibWeb/Parser/ListOfActiveFormattingElements.cpp
@@ -58,7 +58,7 @@ Element* ListOfActiveFormattingElements::last_element_with_tag_name_before_marke
         auto& entry = m_entries[i];
         if (entry.is_marker())
             return nullptr;
-        if (entry.element->tag_name() == tag_name)
+        if (entry.element->local_name() == tag_name)
             return entry.element;
     }
     return nullptr;
diff --git a/Libraries/LibWeb/Parser/StackOfOpenElements.cpp b/Libraries/LibWeb/Parser/StackOfOpenElements.cpp
index 6114d12d59..8dc70ecbbf 100644
--- a/Libraries/LibWeb/Parser/StackOfOpenElements.cpp
+++ b/Libraries/LibWeb/Parser/StackOfOpenElements.cpp
@@ -40,9 +40,9 @@ bool StackOfOpenElements::has_in_scope_impl(const FlyString& tag_name, const Vec
 {
     for (ssize_t i = m_elements.size() - 1; i >= 0; --i) {
         auto& node = m_elements.at(i);
-        if (node.tag_name() == tag_name)
+        if (node.local_name() == tag_name)
             return true;
-        if (list.contains_slow(node.tag_name()))
+        if (list.contains_slow(node.local_name()))
             return false;
     }
     ASSERT_NOT_REACHED();
@@ -59,7 +59,7 @@ bool StackOfOpenElements::has_in_scope_impl(const Element& target_node, const Ve
         auto& node = m_elements.at(i);
         if (&node == &target_node)
             return true;
-        if (list.contains_slow(node.tag_name()))
+        if (list.contains_slow(node.local_name()))
             return false;
     }
     ASSERT_NOT_REACHED();
@@ -107,7 +107,7 @@ bool StackOfOpenElements::contains(const Element& element) const
 bool StackOfOpenElements::contains(const FlyString& tag_name) const
 {
     for (auto& element_on_stack : m_elements) {
-        if (element_on_stack.tag_name() == tag_name)
+        if (element_on_stack.local_name() == tag_name)
             return true;
     }
     return false;
@@ -115,7 +115,7 @@ bool StackOfOpenElements::contains(const FlyString& tag_name) const
 
 void StackOfOpenElements::pop_until_an_element_with_tag_name_has_been_popped(const FlyString& tag_name)
 {
-    while (m_elements.last().tag_name() != tag_name)
+    while (m_elements.last().local_name() != tag_name)
         pop();
     pop();
 }
@@ -127,7 +127,7 @@ Element* StackOfOpenElements::topmost_special_node_below(const Element& formatti
         auto& element = m_elements[i];
         if (&element == &formatting_element)
             break;
-        if (HTMLDocumentParser::is_special_tag(element.tag_name()))
+        if (HTMLDocumentParser::is_special_tag(element.local_name()))
             found_element = &element;
     }
     return found_element;
@@ -137,7 +137,7 @@ Element* StackOfOpenElements::last_element_with_tag_name(const FlyString& tag_na
 {
     for (ssize_t i = m_elements.size() - 1; i >= 0; --i) {
         auto& element = m_elements[i];
-        if (element.tag_name() == tag_name)
+        if (element.local_name() == tag_name)
             return &element;
     }
     return nullptr;