begin messageport, transferable objects, impl

Accept transfer argument for StructuredCloneData::write

Allow structured clone reads to return a boolean

Add Transferable trait

Add basic skeletons to MessagePort

Implement transfer and transfer-receiving steps on MessagePort

Use transfer and transfer_receive in StructuredClone callbacks

Implement MessageChannel

Freeze the array object for the MessageEvent ports attribute

Implement transfer argument on window.postMessage

Use ReentrantMutex instead for MessagePortInternal

Accept origin as a parameter in dispatch_jsval

Fix BorrowMut crash with pending_port_message

Detach port on closure and check for detached during transfer

Enable webmessaging tests

fix webidl

fix

components/script/dom/webidls/Window.webidl

@@ -63,9 +63,8 @@
   unsigned long requestAnimationFrame(FrameRequestCallback callback);
   void cancelAnimationFrame(unsigned long handle);
 
-  //void postMessage(any message, DOMString targetOrigin, optional sequence<Transferable> transfer);
   [Throws]
-  void postMessage(any message, DOMString targetOrigin);
+  void postMessage(any message, USVString targetOrigin, optional sequence<object> transfer /*= []*/);
 
   // also has obsolete members
 };