Have getElementsByClassName() / getElementsByTagName*() return an HTMLCollection

Source/core/html/HTMLAllCollection.cpp

 /*
  * Copyright (C) 2009, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
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  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 66 matching lines @@
         returnValue1 = namedItems.at(0);
         return;
     }
 
     // FIXME: HTML5 specification says this should be a HTMLCollection.
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#htmlallcollection
     returnValue0Enabled = true;
     returnValue0 = NamedNodesCollection::create(namedItems);
 }
 
-PassRefPtr<NodeList> HTMLAllCollection::tags(const AtomicString& name)
+PassRefPtr<HTMLCollection> HTMLAllCollection::tags(const AtomicString& name)
 {
     return ownerNode()->getElementsByTagName(name);
 }
 
 } // namespace WebCore