Oilpan: Remove OffHeapCollectionTrait

Source/core/dom/Fullscreen.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
@@ skipping 596 matching lines @@
     m_fullScreenElementStack.removeLast();
 }
 
 void Fullscreen::pushFullscreenElementStack(Element& element, RequestType requestType)
 {
     m_fullScreenElementStack.append(std::make_pair(&element, requestType));
 }
 
 DEFINE_TRACE(Fullscreen)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_fullScreenElement);
     visitor->trace(m_fullScreenElementStack);
     visitor->trace(m_eventQueue);
+#endif
     WillBeHeapSupplement<Document>::trace(visitor);
     DocumentLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink