Oilpan: Move LifecycleNotifier's hierarchy to Oilpan's heap

Source/core/inspector/AsyncCallTracker.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 66 matching lines @@
         ASSERT(executionContext());
         OwnPtrWillBeRawPtr<ExecutionContextData> self = m_tracker->m_executionContextDataMap.take(executionContext());
         ASSERT_UNUSED(self, self == this);
         ContextLifecycleObserver::contextDestroyed();
         disposeCallChains();
     }
 
     void unobserve()
     {
         disposeCallChains();
-        dispose();
+        setContext(nullptr);
     }
 
     virtual void trace(Visitor* visitor) override
     {
         visitor->trace(m_tracker);
 #if ENABLE(OILPAN)
         visitor->trace(m_timerCallChains);
         visitor->trace(m_animationFrameCallChains);
         visitor->trace(m_eventCallChains);
         visitor->trace(m_xhrCallChains);
@@ skipping 327 matching lines @@
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_executionContextDataMap);
     visitor->trace(m_debuggerAgent);
     visitor->trace(m_instrumentingAgents);
 #endif
     InspectorDebuggerAgent::AsyncCallTrackingListener::trace(visitor);
 }
 
 } // namespace blink