Make DocumentLoader::timing return a reference

Source/web/WebDataSourceImpl.cpp

 /*
  * Copyright (C) 2009 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 97 matching lines @@
 }
 
 void WebDataSourceImpl::setExtraData(ExtraData* extraData)
 {
     // extraData can't be a PassOwnPtr because setExtraData is a WebKit API function.
     m_extraData = adoptPtr(extraData);
 }
 
 void WebDataSourceImpl::setNavigationStartTime(double navigationStart)
 {
-    timing()->setNavigationStart(navigationStart);
+    timing().setNavigationStart(navigationStart);
 }
 
 WebNavigationType WebDataSourceImpl::toWebNavigationType(NavigationType type)
 {
     switch (type) {
     case NavigationTypeLinkClicked:
         return WebNavigationTypeLinkClicked;
     case NavigationTypeFormSubmitted:
         return WebNavigationTypeFormSubmitted;
     case NavigationTypeBackForward:
@@ skipping 27 matching lines @@
 
     ASSERT(nextPluginLoadObserver()->url() == WebURL(request.url()));
     m_pluginLoadObserver = nextPluginLoadObserver().release();
 }
 
 WebDataSourceImpl::~WebDataSourceImpl()
 {
 }
 
 } // namespace blink