NavigationAction should not retain Event.

Source/core/loader/NavigationAction.h

 /*
  * Copyright (C) 2006 Apple Computer, 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 11 matching lines @@
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef NavigationAction_h
 #define NavigationAction_h
 
+#include "core/dom/DOMTimeStamp.h"
 #include "core/events/Event.h"
 #include "core/loader/FrameLoaderTypes.h"
 #include "core/loader/NavigationPolicy.h"
 #include "platform/network/ResourceRequest.h"
 #include "platform/weborigin/KURL.h"
 #include "wtf/Forward.h"
 
 namespace WebCore {
 
     class NavigationAction {
     public:
         NavigationAction();
         NavigationAction(const ResourceRequest&, FrameLoadType = FrameLoadTypeStandard, bool isFormSubmission = false, PassRefPtr<Event> = nullptr);
 
         const ResourceRequest& resourceRequest() const { return m_resourceRequest; }
         NavigationType type() const { return m_type; }
-        Event* event() const { return m_event.get(); }
+        DOMTimeStamp eventTimeStamp() const { return m_eventTimeStamp; }
         NavigationPolicy policy() const { return m_policy; }
         bool shouldOpenInNewWindow() const { return m_policy != NavigationPolicyCurrentTab; }
 
     private:
         ResourceRequest m_resourceRequest;
         NavigationType m_type;
-        RefPtr<Event> m_event;
+        DOMTimeStamp m_eventTimeStamp;
         NavigationPolicy m_policy;
     };
 
 }
 
 #endif