Expose v8 context a MessagePort lives in to give content side code a valid context to (de)serialize…

Source/core/dom/MessagePort.h

Index: Source/core/dom/MessagePort.h
diff --git a/Source/core/dom/MessagePort.h b/Source/core/dom/MessagePort.h
index 69e6565ad5ef94f62d2a6550878394d00f6816fd..9e1601ef9ca115ac20c3cde60b89a839a0074f7f 100644
--- a/Source/core/dom/MessagePort.h
+++ b/Source/core/dom/MessagePort.h
@@ -112,6 +112,8 @@ private:
 
     // WebMessagePortChannelClient implementation.
     virtual void messageAvailable() override;
+    virtual v8::Isolate* scriptIsolate() override;
+    virtual v8::Handle<v8::Context> scriptContext() override;
     void dispatchMessages();
 
     OwnPtr<WebMessagePortChannel> m_entangledChannel;