Remove leak of objects between isolated worlds on custom events.

Source/bindings/v8/custom/V8MessageEventCustom.cpp

Index: Source/bindings/v8/custom/V8MessageEventCustom.cpp
diff --git a/Source/bindings/v8/custom/V8MessageEventCustom.cpp b/Source/bindings/v8/custom/V8MessageEventCustom.cpp
index 906ee9bae55de50670ae76e256caf6a34208e839..7a28b7884c2119aea427c12dfaaa90f7d784e3e1 100644
--- a/Source/bindings/v8/custom/V8MessageEventCustom.cpp
+++ b/Source/bindings/v8/custom/V8MessageEventCustom.cpp
@@ -32,6 +32,7 @@
 #include "V8MessageEvent.h"
 
 #include "bindings/v8/SerializedScriptValue.h"
+#include "bindings/v8/V8HiddenPropertyName.h"
 #include "core/dom/MessageEvent.h"
 
 #include "V8ArrayBuffer.h"
@@ -49,11 +50,7 @@ void V8MessageEvent::dataAttrGetterCustom(v8::Local<v8::String> name, const v8::
     v8::Handle<v8::Value> result;
     switch (event->dataType()) {
     case MessageEvent::DataTypeScriptValue: {
-        ScriptValue scriptValue = event->dataAsScriptValue();
-        if (scriptValue.hasNoValue())
-            result = v8Null(info.GetIsolate());
-        else
-            result = scriptValue.v8Value();
+        result = info.Holder()->GetHiddenValue(V8HiddenPropertyName::data());
         break;
     }
 
@@ -93,7 +90,7 @@ void V8MessageEvent::initMessageEventMethodCustom(const v8::FunctionCallbackInfo
     String typeArg = toWebCoreString(args[0]);
     bool canBubbleArg = args[1]->BooleanValue();
     bool cancelableArg = args[2]->BooleanValue();
-    ScriptValue dataArg = ScriptValue(args[3]);
+    v8::Handle<v8::Value> dataArg = args[3];
     String originArg = toWebCoreString(args[4]);
     String lastEventIdArg = toWebCoreString(args[5]);
 
@@ -111,7 +108,8 @@ void V8MessageEvent::initMessageEventMethodCustom(const v8::FunctionCallbackInfo
         if (!getMessagePortArray(args[7], *portArray, args.GetIsolate()))
             return;
     }
-    event->initMessageEvent(typeArg, canBubbleArg, cancelableArg, dataArg, originArg, lastEventIdArg, sourceArg, portArray.release());
+    args.Holder()->SetHiddenValue(V8HiddenPropertyName::data(), dataArg);
+    event->initMessageEvent(typeArg, canBubbleArg, cancelableArg, originArg, lastEventIdArg, sourceArg, portArray.release());
 }
 
 void V8MessageEvent::webkitInitMessageEventMethodCustom(const v8::FunctionCallbackInfo<v8::Value>& args)