LibWeb: Parse `border-collapse` property for HTML table

Userland/Libraries/LibWeb/CSS/ComputedValues.h

@@ -72,6 +72,7 @@ public:
     static CSS::GridTrackPlacement grid_row_start() { return CSS::GridTrackPlacement::make_auto(); }
     static CSS::Size column_gap() { return CSS::Size::make_auto(); }
     static CSS::Size row_gap() { return CSS::Size::make_auto(); }
+    static CSS::BorderCollapse border_collapse() { return CSS::BorderCollapse::Separate; }
 };
 
 struct BackgroundLayerData {
@@ -192,6 +193,7 @@ public:
     CSS::GridTrackPlacement const& grid_row_start() const { return m_noninherited.grid_row_start; }
     CSS::Size const& column_gap() const { return m_noninherited.column_gap; }
     CSS::Size const& row_gap() const { return m_noninherited.row_gap; }
+    CSS::BorderCollapse border_collapse() const { return m_noninherited.border_collapse; }
 
     CSS::LengthBox const& inset() const { return m_noninherited.inset; }
     const CSS::LengthBox& margin() const { return m_noninherited.margin; }
@@ -316,6 +318,7 @@ protected:
         CSS::GridTrackPlacement grid_row_start { InitialValues::grid_row_start() };
         CSS::Size column_gap { InitialValues::column_gap() };
         CSS::Size row_gap { InitialValues::row_gap() };
+        CSS::BorderCollapse border_collapse { InitialValues::border_collapse() };
     } m_noninherited;
 };
 
@@ -396,6 +399,7 @@ public:
     void set_grid_row_start(CSS::GridTrackPlacement value) { m_noninherited.grid_row_start = value; }
     void set_column_gap(CSS::Size const& column_gap) { m_noninherited.column_gap = column_gap; }
     void set_row_gap(CSS::Size const& row_gap) { m_noninherited.row_gap = row_gap; }
+    void set_border_collapse(CSS::BorderCollapse const& border_collapse) { m_noninherited.border_collapse = border_collapse; }
 
     void set_fill(Color value) { m_inherited.fill = value; }
     void set_stroke(Color value) { m_inherited.stroke = value; }

Userland/Libraries/LibWeb/CSS/Enums.json

@@ -60,6 +60,10 @@
         "content-box",
         "padding-box"
     ],
+    "border-collapse": [
+      "separate",
+      "collapse"
+    ],
     "box-sizing": [
         "border-box",
         "content-box"

Userland/Libraries/LibWeb/CSS/Properties.json

@@ -266,9 +266,8 @@
   "border-collapse": {
     "inherited": true,
     "initial": "separate",
-    "valid-identifiers": [
-      "collapse",
-      "separate"
+    "valid-types": [
+      "border-collapse"
     ]
   },
   "border-left-color": {

Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp

@@ -202,6 +202,8 @@ RefPtr<StyleValue> ResolvedCSSStyleDeclaration::style_value_for_property(Layout:
         return IdentifierStyleValue::create(to_value_id(layout_node.computed_values().border_bottom().line_style));
     case CSS::PropertyID::BorderBottomWidth:
         return LengthStyleValue::create(Length::make_px(layout_node.computed_values().border_bottom().width));
+    case CSS::PropertyID::BorderCollapse:
+        return IdentifierStyleValue::create(to_value_id(layout_node.computed_values().border_collapse()));
     case CSS::PropertyID::BorderLeft: {
         auto border = layout_node.computed_values().border_left();
         auto width = LengthStyleValue::create(Length::make_px(border.width));

Userland/Libraries/LibWeb/CSS/StyleProperties.cpp

@@ -737,4 +737,10 @@ CSS::GridTrackPlacement StyleProperties::grid_row_start() const
     return value->as_grid_track_placement().grid_track_placement();
 }
 
+Optional<CSS::BorderCollapse> StyleProperties::border_collapse() const
+{
+    auto value = property(CSS::PropertyID::BorderCollapse);
+    return value_id_to_border_collapse(value->to_identifier());
+}
+
 }

Userland/Libraries/LibWeb/CSS/StyleProperties.h

@@ -90,6 +90,7 @@ public:
     CSS::GridTrackPlacement grid_column_start() const;
     CSS::GridTrackPlacement grid_row_end() const;
     CSS::GridTrackPlacement grid_row_start() const;
+    Optional<CSS::BorderCollapse> border_collapse() const;
 
     Vector<CSS::Transformation> transformations() const;
     CSS::TransformOrigin transform_origin() const;

Userland/Libraries/LibWeb/Layout/Node.cpp

@@ -605,6 +605,9 @@ void NodeWithStyle::apply_style(const CSS::StyleProperties& computed_style)
 
     computed_values.set_column_gap(computed_style.size_value(CSS::PropertyID::ColumnGap));
     computed_values.set_row_gap(computed_style.size_value(CSS::PropertyID::RowGap));
+
+    if (auto border_collapse = computed_style.border_collapse(); border_collapse.has_value())
+        computed_values.set_border_collapse(border_collapse.value());
 }
 
 bool Node::is_root_element() const