Oilpan: Remove support for tracing of off-heap ListHashSets.

Source/core/events/DOMWindowEventQueue.cpp

 /*
  * Copyright (C) 2010 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 48 matching lines @@
 {
     m_pendingEventTimer->suspendIfNeeded();
 }
 
 DOMWindowEventQueue::~DOMWindowEventQueue()
 {
 }
 
 void DOMWindowEventQueue::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_pendingEventTimer);
     visitor->trace(m_queuedEvents);
+#endif
     EventQueue::trace(visitor);
 }
 
 bool DOMWindowEventQueue::enqueueEvent(PassRefPtrWillBeRawPtr<Event> event)
 {
     if (m_isClosed)
         return false;
 
     ASSERT(event->target());
     InspectorInstrumentation::didEnqueueEvent(event->target(), event.get());
@@ skipping 58 matching lines @@
 void DOMWindowEventQueue::dispatchEvent(PassRefPtrWillBeRawPtr<Event> event)
 {
     EventTarget* eventTarget = event->target();
     if (eventTarget->toDOMWindow())
         eventTarget->toDOMWindow()->dispatchEvent(event, nullptr);
     else
         eventTarget->dispatchEvent(event);
 }
 
 }