Use stricter typing for HTMLCollection named getter

Source/core/html/HTMLCollection.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2011, 2012 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 20 matching lines @@
 
 namespace WebCore {
 
 class HTMLCollection : public ScriptWrappable, public RefCounted<HTMLCollection>, public LiveNodeListBase {
 public:
     static PassRefPtr<HTMLCollection> create(ContainerNode* base, CollectionType);
     virtual ~HTMLCollection();
     virtual void invalidateCache() const OVERRIDE;
 
     // DOM API
-    virtual Node* namedItem(const AtomicString& name) const;
+    virtual Element* namedItem(const AtomicString& name) const;
 
     // Non-DOM API
-    void namedItems(const AtomicString& name, Vector<RefPtr<Node> >&) const;
+    void namedItems(const AtomicString& name, Vector<RefPtr<Element> >&) const;
     bool isEmpty() const
     {
         if (isLengthCacheValid())
             return !cachedLength();
         if (cachedItem())
             return false;
         return !item(0);
     }
     bool hasExactlyOneItem() const
     {
@@ skipping 37 matching lines @@
     mutable unsigned m_isNameCacheValid : 1;
     mutable NodeCacheMap m_idCache;
     mutable NodeCacheMap m_nameCache;
 
     friend class LiveNodeListBase;
 };
 
 } // namespace
 
 #endif