Add support for BeforeUnloadEvent

Source/core/dom/BeforeUnloadEvent.h

Index: Source/core/dom/BeforeUnloadEvent.h
diff --git a/Source/core/dom/BeforeUnloadEvent.h b/Source/core/dom/BeforeUnloadEvent.h
index c3be3467cf9dd7bd24a2b5969b36786f35fb2b60..6fb58bf33326564f2b0a4c5953adbccdc5c5ef54 100644
--- a/Source/core/dom/BeforeUnloadEvent.h
+++ b/Source/core/dom/BeforeUnloadEvent.h
@@ -3,6 +3,7 @@
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006 Apple Computer, Inc.
+ * Copyright (C) 2013 Samsung Electronics.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -25,6 +26,7 @@
 #define BeforeUnloadEvent_h
 
 #include "core/dom/Event.h"
+#include "core/dom/EventNames.h"
 
 namespace WebCore {
 
@@ -37,15 +39,15 @@ namespace WebCore {
             return adoptRef(new BeforeUnloadEvent);
         }
 
-        virtual bool storesResultAsString() const;
-        virtual void storeResult(const String&);
+        void setReturnValue(const String&);

[arv (Not doing code reviews), 2013/08/23 13:56:49]

Now that this is no longer virtual you might as well move the single line
implementation here.

[do-not-use, 2013/08/23 14:27:54]

Done.

+        String returnValue() const { return m_returnValue; }
 
-        String result() const { return m_result; }
+        virtual const AtomicString& interfaceName() const OVERRIDE { return eventNames().interfaceForBeforeUnloadEvent; }
 
     private:
         BeforeUnloadEvent();
 
-        String m_result;
+        String m_returnValue;
     };
 
 } // namespace WebCore