LibWeb: Don't (anonymously) wrap table boxes that are already wrapped

Instead just update the existing wrapper with computed values from the
table box, to insure that upside-down "inheritance" works as expected.

This allows table fixup to run on partially updated layout trees without
adding a new layer of unnecessary wrappers every time.

Libraries/LibWeb/Layout/Node.cpp

@@ -1109,6 +1109,11 @@ GC::Ref<NodeWithStyle> NodeWithStyle::create_anonymous_wrapper() const
     return *wrapper;
 }
 
+void NodeWithStyle::set_computed_values(NonnullOwnPtr<CSS::ComputedValues> computed_values)
+{
+    m_computed_values = move(computed_values);
+}
+
 void NodeWithStyle::reset_table_box_computed_values_used_by_wrapper_to_init_values()
 {
     VERIFY(this->display().is_table_inside());

Libraries/LibWeb/Layout/Node.h

@@ -191,6 +191,9 @@ public:
     // https://drafts.csswg.org/css-ui/#propdef-user-select
     CSS::UserSelect user_select_used_value() const;
 
+    [[nodiscard]] bool has_been_wrapped_in_table_wrapper() const { return m_has_been_wrapped_in_table_wrapper; }
+    void set_has_been_wrapped_in_table_wrapper(bool value) { m_has_been_wrapped_in_table_wrapper = value; }
+
 protected:
     Node(DOM::Document&, DOM::Node*);
 
@@ -211,6 +214,8 @@ private:
     bool m_is_flex_item { false };
     bool m_is_grid_item { false };
 
+    bool m_has_been_wrapped_in_table_wrapper { false };
+
     GeneratedFor m_generated_for { GeneratedFor::NotGenerated };
 
     u32 m_initial_quote_nesting_level { 0 };
@@ -240,6 +245,8 @@ public:
 
     virtual void visit_edges(Cell::Visitor& visitor) override;
 
+    void set_computed_values(NonnullOwnPtr<CSS::ComputedValues>);
+
 protected:
     NodeWithStyle(DOM::Document&, DOM::Node*, GC::Ref<CSS::ComputedProperties>);
     NodeWithStyle(DOM::Document&, DOM::Node*, NonnullOwnPtr<CSS::ComputedValues>);

Libraries/LibWeb/Layout/TreeBuilder.cpp

@@ -784,6 +784,11 @@ Vector<GC::Root<Box>> TreeBuilder::generate_missing_parents(NodeWithStyle& root)
 
         // An anonymous table-wrapper box must be generated around each table-root.
         if (parent.display().is_table_inside()) {
+            if (parent.has_been_wrapped_in_table_wrapper()) {
+                VERIFY(parent.parent());
+                VERIFY(parent.parent()->is_table_wrapper());
+                return TraversalDecision::Continue;
+            }
             table_roots_to_wrap.append(parent);
         }
 
@@ -797,6 +802,12 @@ Vector<GC::Root<Box>> TreeBuilder::generate_missing_parents(NodeWithStyle& root)
         auto wrapper_computed_values = table_box->computed_values().clone_inherited_values();
         table_box->transfer_table_box_computed_values_to_wrapper_computed_values(*wrapper_computed_values);
 
+        if (parent.is_table_wrapper()) {
+            auto& existing_wrapper = static_cast<TableWrapper&>(parent);
+            existing_wrapper.set_computed_values(move(wrapper_computed_values));
+            continue;
+        }
+
         auto wrapper = parent.heap().allocate<TableWrapper>(parent.document(), nullptr, move(wrapper_computed_values));
 
         parent.remove_child(*table_box);
@@ -806,6 +817,8 @@ Vector<GC::Root<Box>> TreeBuilder::generate_missing_parents(NodeWithStyle& root)
             parent.insert_before(*wrapper, *nearest_sibling);
         else
             parent.append_child(*wrapper);
+
+        table_box->set_has_been_wrapped_in_table_wrapper(true);
     }
 
     return table_roots_to_wrap;