Use stricter typing for NodeLists throughout the code base

Source/core/dom/NamedNodesCollection.h

 /*
 * Copyright (C) 2009 Google 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:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
@@ skipping 23 matching lines @@
 #include "core/dom/Element.h"
 #include "core/dom/NodeList.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 class NamedNodesCollection FINAL : public NodeList {
 public:
-    static PassRefPtrWillBeRawPtr<NodeList> create(const WillBeHeapVector<RefPtrWillBeMember<Element> >& nodes)
+    static PassRefPtrWillBeRawPtr<NamedNodesCollection> create(const WillBeHeapVector<RefPtrWillBeMember<Element> >& nodes)
     {
         return adoptRefWillBeNoop(new NamedNodesCollection(nodes));
     }
 
     virtual unsigned length() const OVERRIDE { return m_nodes.size(); }
     virtual Element* item(unsigned) const OVERRIDE;
 
     virtual void trace(Visitor*) OVERRIDE;
 
 private:
     explicit NamedNodesCollection(const WillBeHeapVector<RefPtrWillBeMember<Element> > nodes)
         : m_nodes(nodes) { }
 
     WillBeHeapVector<RefPtrWillBeMember<Element> > m_nodes;
 };
 
 } // namespace WebCore
 
 #endif // NamedNodesCollection_h