Oilpan: Remove support for tracing off-heap HashSets.

Source/core/page/Page.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All Rights Reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.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
  * version 2 of the License, or (at your option) any later version.
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 580 matching lines @@
     return static_cast<PageLifecycleNotifier&>(LifecycleContext<Page>::lifecycleNotifier());
 }
 
 PassOwnPtr<LifecycleNotifier<Page> > Page::createLifecycleNotifier()
 {
     return PageLifecycleNotifier::create(this);
 }
 
 void Page::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_dragCaretController);
     visitor->trace(m_dragController);
     visitor->trace(m_contextMenuController);
     visitor->trace(m_pointerLockController);
     visitor->trace(m_undoStack);
     visitor->trace(m_validationMessageClient);
     visitor->trace(m_multisamplingChangedObservers);
     visitor->trace(m_frameHost);
+#endif
     WillBeHeapSupplementable<Page>::trace(visitor);
 }
 
 void Page::willBeDestroyed()
 {
     RefPtr<Frame> mainFrame = m_mainFrame;
 
     if (mainFrame->isLocalFrame())
         toLocalFrame(mainFrame.get())->loader().frameDetached();
 
@@ skipping 35 matching lines @@
     , spellCheckerClient(0)
     , storageClient(0)
 {
 }
 
 Page::PageClients::~PageClients()
 {
 }
 
 } // namespace WebCore