Oilpan: avoid using WeakPtr<> for heap residing objects.

Source/core/dom/MainThreadTaskRunner.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:
  * 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 30 matching lines @@
     MainThreadTask(WeakPtrWillBeRawPtr<MainThreadTaskRunner> runner, PassOwnPtr<ExecutionContextTask> task, bool isInspectorTask)
         : m_runner(runner)
         , m_task(task)
         , m_isInspectorTask(isInspectorTask)
     {
     }
 
     void run() override;
 
 private:
-#if ENABLE(OILPAN)
-    CrossThreadWeakPersistent<MainThreadTaskRunner> m_runner;
-#else
-    WeakPtr<MainThreadTaskRunner> m_runner;
-#endif
+    WeakPtrWillBeCrossThreadWeakPersistent<MainThreadTaskRunner> m_runner;
     OwnPtr<ExecutionContextTask> m_task;
     bool m_isInspectorTask;
 };
 
 void MainThreadTask::run()
 {
     ASSERT(isMainThread());
 
     if (!m_runner.get())
         return;
@@ skipping 79 matching lines @@
 WeakPtrWillBeRawPtr<MainThreadTaskRunner> MainThreadTaskRunner::createWeakPointerToSelf()
 {
 #if ENABLE(OILPAN)
     return this;
 #else
     return m_weakFactory.createWeakPtr();
 #endif
 }
 
 } // namespace