Remove leak of objects between isolated worlds on custom events.

Source/core/dom/PopStateEvent.h

Index: Source/core/dom/PopStateEvent.h
diff --git a/Source/core/dom/PopStateEvent.h b/Source/core/dom/PopStateEvent.h
index 1c59d0f302dd0686f8adb64c788c2cfc4dbecb15..ddc727b5a8bfa7bb0c8caaaa63359b0d586aecc8 100644
--- a/Source/core/dom/PopStateEvent.h
+++ b/Source/core/dom/PopStateEvent.h
@@ -27,7 +27,6 @@
 #ifndef PopStateEvent_h
 #define PopStateEvent_h
 
-#include "bindings/v8/ScriptValue.h"
 #include "core/dom/Event.h"
 
 namespace WebCore {
@@ -35,7 +34,7 @@ namespace WebCore {
 struct PopStateEventInit : public EventInit {
     PopStateEventInit();
 
-    ScriptValue state;
+    bool stateIsSet;
 };
 
 class History;
@@ -49,19 +48,20 @@ public:
     static PassRefPtr<PopStateEvent> create(const AtomicString&, const PopStateEventInit&);
 
     PassRefPtr<SerializedScriptValue> serializedState() const { return m_serializedState; }
-    const ScriptValue& state() const { return m_state; }
     History* history() const { return m_history.get(); }
 
     virtual const AtomicString& interfaceName() const;
 
+    bool isStateSet() const { return m_stateIsSet; }
+
 private:
     PopStateEvent();
     PopStateEvent(const AtomicString&, const PopStateEventInit&);
     explicit PopStateEvent(PassRefPtr<SerializedScriptValue>, PassRefPtr<History>);
 
-    ScriptValue m_state;
     RefPtr<SerializedScriptValue> m_serializedState;
     RefPtr<History> m_history;
+    bool m_stateIsSet;
 };
 
 } // namespace WebCore