Make collection caching code more consistent

Source/core/html/HTMLFormElement.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, 2007, 2008, 2009 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 15 matching lines @@
 #include "core/html/HTMLFormElement.h"
 
 #include "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/ScriptEventListener.h"
 #include "bindings/core/v8/V8DOMActivityLogger.h"
 #include "core/HTMLNames.h"
 #include "core/dom/Attribute.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/IdTargetObserverRegistry.h"
+#include "core/dom/NodeListsNodeData.h"
 #include "core/events/AutocompleteErrorEvent.h"
 #include "core/events/Event.h"
 #include "core/events/GenericEventQueue.h"
 #include "core/events/ScopedEventQueue.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/UseCounter.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "core/html/HTMLCollection.h"
 #include "core/html/HTMLDialogElement.h"
@@ skipping 536 matching lines @@
 void HTMLFormElement::didAssociateByParser()
 {
     if (!m_didFinishParsingChildren)
         return;
     m_hasElementsAssociatedByParser = true;
     UseCounter::count(document(), UseCounter::FormAssociationByParser);
 }
 
 PassRefPtrWillBeRawPtr<HTMLFormControlsCollection> HTMLFormElement::elements()
 {
-    return toHTMLFormControlsCollection(ensureCachedHTMLCollection(FormControls).get());
+    return ensureCachedCollection<HTMLFormControlsCollection>(FormControls);
 }
 
 void HTMLFormElement::collectAssociatedElements(Node& root, FormAssociatedElement::List& elements) const
 {
     elements.clear();
     for (HTMLElement* element = Traversal<HTMLElement>::firstWithin(root); element; element = Traversal<HTMLElement>::next(*element)) {
         FormAssociatedElement* associatedElement = 0;
         if (element->isFormControlElement())
             associatedElement = toHTMLFormControlElement(element);
         else if (isHTMLObjectElement(*element))
@@ skipping 223 matching lines @@
 }
 
 void HTMLFormElement::setDemoted(bool demoted)
 {
     if (demoted)
         UseCounter::count(document(), UseCounter::DemotedFormElement);
     m_wasDemoted = demoted;
 }
 
 } // namespace