Node.contains should return true for nodes in Shadow DOM.

Source/core/dom/Node.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, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 964 matching lines @@
 
 bool Node::contains(const Node* node) const
 {
     if (!node)
         return false;
     return this == node || node->isDescendantOf(this);
 }
 
 bool Node::containsIncludingShadowDOM(const Node* node) const
 {
-    for (; node; node = node->parentOrShadowHostNode()) {
-        if (node == this)
-            return true;
+    if (!node)
+        return false;
+
+    if (this == node)
+        return true;
+
+    if (document() != node->document())
+        return false;
+
+    if (inDocument() != node->inDocument())
+        return false;
+
+    bool hasChildren = isContainerNode() && toContainerNode(this)->hasChildNodes();
+    bool hasShadow = isElementNode() && toElement(this)->shadow();
+    if (!hasChildren && !hasShadow)
+        return false;
+
+    for (; node; node = node->shadowHost()) {
+        if (treeScope() == node->treeScope())
+            return contains(node);
     }
+
     return false;
 }
 
 bool Node::containsIncludingHostElements(const Node* node) const
 {
     while (node) {
         if (node == this)
             return true;
         if (node->isDocumentFragment() && static_cast<const DocumentFragment*>(node)->isTemplateContent())
             node = static_cast<const TemplateContentDocumentFragment*>(node)->host();
@@ skipping 1695 matching lines @@
         node->showTreeForThis();
 }
 
 void showNodePath(const WebCore::Node* node)
 {
     if (node)
         node->showNodePathForThis();
 }
 
 #endif