Fix an optimisation in ContainerNode::notifyNodeInsertedInternal

third_party/WebKit/Source/core/dom/ContainerNode.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 818 matching lines @@
     }
 }
 
 void ContainerNode::notifyNodeInsertedInternal(Node& root, NodeVector& postInsertionNotificationTargets)
 {
     EventDispatchForbiddenScope assertNoEventDispatch;
     ScriptForbiddenScope forbidScript;
 
     for (Node& node : NodeTraversal::inclusiveDescendantsOf(root)) {
         // As an optimization we don't notify leaf nodes when when inserting
-        // into detached subtrees.
-        if (!inDocument() && !node.isContainerNode())
+        // into detached subtrees that are not in a shadow tree.
+        if (!inDocument() && !isInShadowTree() && !node.isContainerNode())
             continue;
         if (Node::InsertionShouldCallDidNotifySubtreeInsertions == node.insertedInto(this))
             postInsertionNotificationTargets.append(&node);
         for (ShadowRoot* shadowRoot = node.youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot())
             notifyNodeInsertedInternal(*shadowRoot, postInsertionNotificationTargets);
     }
 }
 
 void ContainerNode::notifyNodeRemoved(Node& root)
 {
@@ skipping 673 matching lines @@
         return true;
 
     if (node->isElementNode() && toElement(node)->shadow())
         return true;
 
     return false;
 }
 #endif
 
 } // namespace blink