Make sure the rootNode of a LiveNodeListBase is always a ContainerNode

Source/core/dom/ChildNodeList.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, 2007, 2008 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 10 matching lines @@
  */
 
 #include "config.h"
 #include "core/dom/ChildNodeList.h"
 
 #include "core/dom/Element.h"
 #include "core/dom/NodeRareData.h"
 
 namespace WebCore {
 
-ChildNodeList::ChildNodeList(PassRefPtr<Node> node)
+ChildNodeList::ChildNodeList(PassRefPtr<ContainerNode> node)
     : LiveNodeList(node, ChildNodeListType, DoNotInvalidateOnAttributeChanges)
 {
 }
 
 ChildNodeList::~ChildNodeList()
 {
     ownerNode()->nodeLists()->removeChildNodeList(this);
 }
 
 bool ChildNodeList::nodeMatches(const Element& testNode) const
 {
     // This function will be called only by LiveNodeList::namedItem,
     // for an element that was located with getElementById.
     return testNode.parentNode() == rootNode();
 }
 
 } // namespace WebCore