LibWeb: Add CSS::Display enum and StyleProperties::display()

The display property is not interesting after we've built the layout
tree, so we don't have to move it into LayoutStyle.

Libraries/LibWeb/CSS/StyleProperties.cpp

@@ -244,4 +244,29 @@ CSS::TextAlign StyleProperties::text_align() const
     return CSS::TextAlign::Left;
 }
 
+CSS::Display StyleProperties::display() const
+{
+    auto display = string_or_fallback(CSS::PropertyID::Display, "inline");
+    if (display == "none")
+        return CSS::Display::None;
+    if (display == "block")
+        return CSS::Display::Block;
+    if (display == "inline")
+        return CSS::Display::Inline;
+    if (display == "inline-block")
+        return CSS::Display::InlineBlock;
+    if (display == "list-item")
+        return CSS::Display::ListItem;
+    if (display == "table")
+        return CSS::Display::Table;
+    if (display == "table-row")
+        return CSS::Display::TableRow;
+    if (display == "table-cell")
+        return CSS::Display::TableCell;
+    if (display == "table-row-group")
+        return CSS::Display::TableRowGroup;
+    dbg() << "Unknown display type: _" << display << "_";
+    return CSS::Display::Block;
+}
+
 }

Libraries/LibWeb/CSS/StyleProperties.h

@@ -60,6 +60,7 @@ public:
     String string_or_fallback(CSS::PropertyID, const StringView& fallback) const;
     Color color_or_fallback(CSS::PropertyID, const Document&, Color fallback) const;
     CSS::TextAlign text_align() const;
+    CSS::Display display() const;
 
     const Gfx::Font& font() const
     {

Libraries/LibWeb/CSS/StyleValue.h

@@ -123,6 +123,18 @@ enum class TextAlign {
     VendorSpecificCenter,
 };
 
+enum class Display {
+    None,
+    Block,
+    Inline,
+    InlineBlock,
+    ListItem,
+    Table,
+    TableRow,
+    TableCell,
+    TableRowGroup,
+};
+
 }
 
 class StyleValue : public RefCounted<StyleValue> {

Libraries/LibWeb/DOM/Element.cpp

@@ -111,36 +111,34 @@ RefPtr<LayoutNode> Element::create_layout_node(const StyleProperties* parent_sty
 {
     auto style = document().style_resolver().resolve_style(*this, parent_style);
     const_cast<Element&>(*this).m_resolved_style = style;
-    auto display = style->string_or_fallback(CSS::PropertyID::Display, "inline");
+    auto display = style->display();
 
-    if (display == "none")
+    if (display == CSS::Display::None)
         return nullptr;
 
     if (tag_name() == "noscript" && document().is_scripting_enabled())
         return nullptr;
 
-    if (display == "block")
+    if (display == CSS::Display::Block)
         return adopt(*new LayoutBlock(this, move(style)));
-    if (display == "inline")
+    if (display == CSS::Display::Inline)
         return adopt(*new LayoutInline(*this, move(style)));
-    if (display == "list-item")
+    if (display == CSS::Display::ListItem)
         return adopt(*new LayoutListItem(*this, move(style)));
-    if (display == "table")
+    if (display == CSS::Display::Table)
         return adopt(*new LayoutTable(*this, move(style)));
-    if (display == "table-row")
+    if (display == CSS::Display::TableRow)
         return adopt(*new LayoutTableRow(*this, move(style)));
-    if (display == "table-cell")
+    if (display == CSS::Display::TableCell)
         return adopt(*new LayoutTableCell(*this, move(style)));
-    if (display == "table-row-group")
+    if (display == CSS::Display::TableRowGroup)
         return adopt(*new LayoutTableRowGroup(*this, move(style)));
-    if (display == "inline-block") {
+    if (display == CSS::Display::InlineBlock) {
         auto inline_block = adopt(*new LayoutBlock(this, move(style)));
         inline_block->set_inline(true);
         return inline_block;
     }
-
+    ASSERT_NOT_REACHED();
-    dbg() << "Unknown display type: _" << display << "_";
-    return adopt(*new LayoutBlock(this, move(style)));
 }
 
 void Element::parse_attribute(const FlyString& name, const String& value)
@@ -169,7 +167,7 @@ static StyleDifference compute_style_difference(const StyleProperties& old_style
     bool needs_repaint = false;
     bool needs_relayout = false;
 
-    if (new_style.string_or_fallback(CSS::PropertyID::Display, "block") != old_style.string_or_fallback(CSS::PropertyID::Color, "block"))
+    if (new_style.display() != old_style.display())
         needs_relayout = true;
 
     if (new_style.color_or_fallback(CSS::PropertyID::Color, document, Color::Black) != old_style.color_or_fallback(CSS::PropertyID::Color, document, Color::Black))
@@ -195,7 +193,7 @@ void Element::recompute_style()
     auto style = document().style_resolver().resolve_style(*this, &parent_layout_node->specified_style());
     m_resolved_style = style;
     if (!layout_node()) {
-        if (style->string_or_fallback(CSS::PropertyID::Display, "inline") == "none")
+        if (style->display() == CSS::Display::None)
             return;
         // We need a new layout tree here!
         LayoutTreeBuilder tree_builder;

Libraries/LibWeb/DOM/HTMLCanvasElement.cpp

@@ -58,8 +58,7 @@ unsigned HTMLCanvasElement::height() const
 RefPtr<LayoutNode> HTMLCanvasElement::create_layout_node(const StyleProperties* parent_style) const
 {
     auto style = document().style_resolver().resolve_style(*this, parent_style);
-    auto display = style->string_or_fallback(CSS::PropertyID::Display, "inline");
+    if (style->display() == CSS::Display::None)
-    if (display == "none")
         return nullptr;
     return adopt(*new LayoutCanvas(*this, move(style)));
 }

Libraries/LibWeb/DOM/HTMLImageElement.cpp

@@ -71,8 +71,7 @@ void HTMLImageElement::parse_attribute(const FlyString& name, const String& valu
 RefPtr<LayoutNode> HTMLImageElement::create_layout_node(const StyleProperties* parent_style) const
 {
     auto style = document().style_resolver().resolve_style(*this, parent_style);
-    auto display = style->string_or_fallback(CSS::PropertyID::Display, "inline");
+    if (style->display() == CSS::Display::None)
-    if (display == "none")
         return nullptr;
     return adopt(*new LayoutImage(*this, move(style), m_image_loader));
 }

Libraries/LibWeb/DOM/HTMLInputElement.cpp

@@ -56,8 +56,7 @@ RefPtr<LayoutNode> HTMLInputElement::create_layout_node(const StyleProperties* p
         return nullptr;
 
     auto style = document().style_resolver().resolve_style(*this, parent_style);
-    auto display = style->string_or_fallback(CSS::PropertyID::Display, "inline");
+    if (style->display() == CSS::Display::None)
-    if (display == "none")
         return nullptr;
 
     RefPtr<GUI::Widget> widget;

Libraries/LibWeb/DOM/HTMLObjectElement.cpp

@@ -67,8 +67,7 @@ RefPtr<LayoutNode> HTMLObjectElement::create_layout_node(const StyleProperties*
         return HTMLElement::create_layout_node(parent_style);
 
     auto style = document().style_resolver().resolve_style(*this, parent_style);
-    auto display = style->string_or_fallback(CSS::PropertyID::Display, "inline");
+    if (style->display() == CSS::Display::None)
-    if (display == "none")
         return nullptr;
     if (m_image_loader.has_image())
         return adopt(*new LayoutImage(*this, move(style), m_image_loader));