LibWeb: Add opt-in tracing of set_needs_layout() calls with reason

Author: https://github.com/awesomekling
Commit: 2abbf99a95
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3852

Libraries/LibWeb/DOM/Node.cpp

@@ -1405,7 +1405,7 @@ void Node::set_needs_layout_tree_update(bool value)
                 break;
             ancestor->m_child_needs_layout_tree_update = true;
         }
-        document().set_needs_layout();
+        document().set_needs_layout(SetNeedsLayoutReason::LayoutTreeUpdate);
     }
 }