NavigationAction should not retain Event.

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 88 matching lines @@
     return DocumentLoader::replacesCurrentHistoryItem();
 }
 
 WebNavigationType WebDataSourceImpl::navigationType() const
 {
     return toWebNavigationType(triggeringAction().type());
 }
 
 double WebDataSourceImpl::triggeringEventTime() const
 {
-    if (!triggeringAction().event())
-        return 0.0;
-
     // DOMTimeStamp uses units of milliseconds.
-    return convertDOMTimeStampToSeconds(triggeringAction().event()->timeStamp());
+    return convertDOMTimeStampToSeconds(triggeringAction().eventTimeStamp());
 }
 
 WebDataSource::ExtraData* WebDataSourceImpl::extraData() const
 {
     return m_extraData.get();
 }
 
 void WebDataSourceImpl::setExtraData(ExtraData* extraData)
 {
     // extraData can't be a PassOwnPtr because setExtraData is a WebKit API function.
@@ skipping 43 matching lines @@
 
     ASSERT(nextPluginLoadObserver()->url() == WebURL(request.url()));
     m_pluginLoadObserver = nextPluginLoadObserver().release();
 }
 
 WebDataSourceImpl::~WebDataSourceImpl()
 {
 }
 
 } // namespace blink