Make sure the rootNode of a LiveNodeListBase is always a ContainerNode

Source/core/html/HTMLNameCollection.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007 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 15 matching lines @@
 #include "core/html/HTMLCollection.h"
 
 #include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 
 class Document;
 
 class HTMLNameCollection FINAL : public HTMLCollection {
 public:
-    static PassRefPtr<HTMLNameCollection> create(Node* document, CollectionType type, const AtomicString& name)
+    static PassRefPtr<HTMLNameCollection> create(ContainerNode* document, CollectionType type, const AtomicString& name)
     {
         return adoptRef(new HTMLNameCollection(document, type, name));
     }
 
     ~HTMLNameCollection();
 
 private:
-    HTMLNameCollection(Node*, CollectionType, const AtomicString& name);
+    HTMLNameCollection(ContainerNode*, CollectionType, const AtomicString& name);
 
     virtual Element* virtualItemAfter(Element*) const OVERRIDE;
 
     AtomicString m_name;
 };
 
 }
 
 #endif