LibWeb: Distinguish parent/child on style invalidation for DOM insertion

Author: https://github.com/awesomekling
Commit: 7d644ecd50
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1483
Reviewed-by: https://github.com/kalenikaliaksandr

Userland/Libraries/LibWeb/DOM/Node.cpp

@@ -682,7 +682,7 @@ void Node::insert_before(JS::NonnullGCPtr<Node> node, JS::GCPtr<Node> child, boo
 
     if (is_connected()) {
         // FIXME: This will need to become smarter when we implement the :has() selector.
-        invalidate_style(StyleInvalidationReason::NodeInsertBefore);
+        invalidate_style(StyleInvalidationReason::ParentOfInsertedNode);
         document().invalidate_layout_tree();
     }
 

Userland/Libraries/LibWeb/DOM/Node.h

@@ -72,6 +72,7 @@ enum class FragmentSerializationMode {
     X(NodeRemove)                                   \
     X(NodeSetTextContent)                           \
     X(Other)                                        \
+    X(ParentOfInsertedNode)                         \
     X(SetSelectorText)                              \
     X(SettingsChange)                               \
     X(StyleSheetDeleteRule)                         \