LibWeb: Improvements to Node::invalidate_style()

- Access members directly instead of going through accessors,
  avoiding a lot of redundant traversal done by accessors.

- Cross shadow boundaries and make sure that shadow trees get their
  dirty bits updated as well.

- Do the minimum amount of traversal needed when setting the "child
  needs style update" bit upwards through ancestors.

1 files changed, 14 insertions, 2 deletions

diff --git a/Userland/Libraries/LibWeb/DOM/Node.cpp b/Userland/Libraries/LibWeb/DOM/Node.cpp
index c55999285a..3c147f58f7 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Node.cpp
@@ -176,10 +176,22 @@ void Node::set_node_value(const String& value)
 
 void Node::invalidate_style()
 {
-    for_each_in_inclusive_subtree_of_type<Element>([&](auto& element) {
-        element.set_needs_style_update(true);
+    for_each_in_inclusive_subtree([&](Node& node) {
+        node.m_needs_style_update = true;
+        if (node.has_children())
+            node.m_child_needs_style_update = true;
+        if (auto* shadow_root = node.is_element() ? static_cast<DOM::Element&>(node).shadow_root() : nullptr) {
+            shadow_root->m_needs_style_update = true;
+            if (shadow_root->has_children())
+                shadow_root->m_child_needs_style_update = true;
+        }
         return IterationDecision::Continue;
     });
+    for (auto* ancestor = parent_or_shadow_host(); ancestor; ancestor = parent_or_shadow_host()) {
+        if (ancestor->m_child_needs_style_update)
+            break;
+        ancestor->m_child_needs_style_update = true;
+    }
     document().schedule_style_update();
 }