LibHTML: Detect hovering over links

HtmlView now calls Node::enclosing_link_element() to find the nearest
ancestor <a> element.

This patch also adds HTMLElement and HTMLAnchorElement.

Libraries/LibHTML/DOM/HTMLAnchorElement.cpp

@@ -0,0 +1,10 @@
+#include <LibHTML/DOM/HTMLAnchorElement.h>
+
+HTMLAnchorElement::HTMLAnchorElement(Document& document, const String& tag_name)
+    : HTMLElement(document, tag_name)
+{
+}
+
+HTMLAnchorElement::~HTMLAnchorElement()
+{
+}

Libraries/LibHTML/DOM/HTMLAnchorElement.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <LibHTML/DOM/HTMLElement.h>
+
+class HTMLAnchorElement : public HTMLElement {
+public:
+    HTMLAnchorElement(Document&, const String& tag_name);
+    virtual ~HTMLAnchorElement() override;
+
+    String href() const { return attribute("href"); }
+};

Libraries/LibHTML/DOM/HTMLElement.cpp

@@ -0,0 +1,10 @@
+#include <LibHTML/DOM/HTMLElement.h>
+
+HTMLElement::HTMLElement(Document& document, const String& tag_name)
+    : Element(document, tag_name)
+{
+}
+
+HTMLElement::~HTMLElement()
+{
+}

Libraries/LibHTML/DOM/HTMLElement.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <LibHTML/DOM/Element.h>
+
+class HTMLElement : public Element {
+public:
+    HTMLElement(Document&, const String& tag_name);
+    virtual ~HTMLElement() override;
+};

Libraries/LibHTML/DOM/Node.cpp

@@ -1,5 +1,6 @@
 #include <LibHTML/DOM/Node.h>
 #include <LibHTML/DOM/Element.h>
+#include <LibHTML/DOM/HTMLAnchorElement.h>
 #include <LibHTML/CSS/StyleResolver.h>
 #include <LibHTML/Layout/LayoutNode.h>
 #include <LibHTML/Layout/LayoutBlock.h>
@@ -73,3 +74,10 @@ RefPtr<LayoutNode> Node::create_layout_tree(const StyleResolver& resolver, const
         }
     return layout_node;
 }
+
+const HTMLAnchorElement* Node::enclosing_link_element() const
+{
+    if (is_element() && tag_name().to_lowercase() == "a")
+        return static_cast<const HTMLAnchorElement*>(this);
+    return parent() ? parent()->enclosing_link_element() : nullptr;
+}

Libraries/LibHTML/DOM/Node.h

@@ -14,6 +14,7 @@ enum class NodeType : unsigned {
 };
 
 class Document;
+class HTMLAnchorElement;
 class ParentNode;
 class LayoutNode;
 class StyleResolver;
@@ -37,6 +38,8 @@ public:
     Document& document() { return m_document; }
     const Document& document() const { return m_document; }
 
+    const HTMLAnchorElement* enclosing_link_element() const;
+
 protected:
     Node(Document&, NodeType);