Have LifecycleContext::lifecycleNotifier() return a reference

Source/core/dom/ExecutionContext.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2012 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
@@ skipping 107 matching lines @@
     int circularSequentialID();
 
     void didChangeTimerAlignmentInterval();
 
     SandboxFlags sandboxFlags() const { return m_sandboxFlags; }
     bool isSandboxed(SandboxFlags mask) const { return m_sandboxFlags & mask; }
     void enforceSandboxFlags(SandboxFlags mask);
 
 protected:
 
-    ContextLifecycleNotifier* lifecycleNotifier();
+    ContextLifecycleNotifier& lifecycleNotifier();
 
 private:
     friend class DOMTimer; // For installNewTimeout() and removeTimeoutByID() below.
 
     bool dispatchErrorEvent(PassRefPtr<ErrorEvent>, AccessControlStatus);
 
     void closeMessagePorts();
 
     virtual void refExecutionContext() = 0;
     virtual void derefExecutionContext() = 0;
@@ skipping 23 matching lines @@
 
     // The location of this member is important; to make sure contextDestroyed() notification on
     // ExecutionContext's members (notably m_timeouts) is called before they are destructed,
     // m_lifecycleNotifer should be placed *after* such members.
     OwnPtr<ContextLifecycleNotifier> m_lifecycleNotifier;
 };
 
 } // namespace WebCore
 
 #endif // ExecutionContext_h