Have LifecycleContext::lifecycleNotifier() return a reference

Source/core/dom/Document.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 1046 matching lines @@
 
     void didAssociateFormControl(Element*);
 
     void addConsoleMessageWithRequestIdentifier(MessageSource, MessageLevel, const String& message, unsigned long requestIdentifier);
 
     virtual DOMWindow* executingWindow() OVERRIDE { return domWindow(); }
     virtual void userEventWasHandled() OVERRIDE { resetLastHandledUserGestureTimestamp(); }
 
     // Can never return null.
     FontFaceSet* fonts();
-    DocumentLifecycleNotifier* lifecycleNotifier();
+    DocumentLifecycleNotifier& lifecycleNotifier();
     bool isActive() const { return m_lifecyle.state() == DocumentLifecycle::Active; }
 
     enum HttpRefreshType {
         HttpRefreshFromHeader,
         HttpRefreshFromMetaTag
     };
     void maybeHandleHttpRefresh(const String&, HttpRefreshType);
 
 protected:
     Document(const DocumentInit&, DocumentClassFlags = DefaultDocumentClass);
@@ skipping 367 matching lines @@
 inline bool Node::isDocumentNode() const
 {
     return this == documentInternal();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h