Make sure the rootNode of a LiveNodeListBase is always a ContainerNode

Source/core/html/LabelsNodeList.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.
  * Copyright (C) 2010 Nokia 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
@@ skipping 15 matching lines @@
 
 #include "HTMLNames.h"
 #include "core/dom/Element.h"
 #include "core/dom/NodeRareData.h"
 #include "core/html/HTMLLabelElement.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
-LabelsNodeList::LabelsNodeList(Node* ownerNode)
+LabelsNodeList::LabelsNodeList(ContainerNode* ownerNode)
     : LiveNodeList(ownerNode, LabelsNodeListType, InvalidateOnForAttrChange, NodeListIsRootedAtDocument)
 {
 }
 
 LabelsNodeList::~LabelsNodeList()
 {
     ownerNode()->nodeLists()->removeCacheWithAtomicName(this, LabelsNodeListType, starAtom);
 }
 
 bool LabelsNodeList::nodeMatches(const Element& testNode) const
 {
     return testNode.hasTagName(labelTag) && toHTMLLabelElement(testNode).control() == ownerNode();
 }
 
 } // namespace WebCore