Oilpan: move LiveNodeList collections to the heap.

Source/core/html/HTMLFieldSetElement.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, 2005, 2006, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * 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 82 matching lines @@
 RenderObject* HTMLFieldSetElement::createRenderer(RenderStyle*)
 {
     return new RenderFieldset(this);
 }
 
 HTMLLegendElement* HTMLFieldSetElement::legend() const
 {
     return Traversal<HTMLLegendElement>::firstChild(*this);
 }
 
-PassRefPtr<HTMLCollection> HTMLFieldSetElement::elements()
+PassRefPtrWillBeRawPtr<HTMLCollection> HTMLFieldSetElement::elements()
 {
     return ensureCachedHTMLCollection(FormControls);
 }
 
 void HTMLFieldSetElement::refreshElementsIfNeeded() const
 {
     uint64_t docVersion = document().domTreeVersion();
     if (m_documentVersion == docVersion)
         return;
 
@@ skipping 14 matching lines @@
     }
 }
 
 const FormAssociatedElement::List& HTMLFieldSetElement::associatedElements() const
 {
     refreshElementsIfNeeded();
     return m_associatedElements;
 }
 
 } // namespace