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/dissimilaroriginwindow.rs

@@ -150,7 +150,8 @@ impl DissimilarOriginWindowMethods for DissimilarOriginWindow {
 
         // Step 1-2, 6-8.
         // TODO(#12717): Should implement the `transfer` argument.
-        let data = StructuredCloneData::write(*cx, message)?;
+        rooted!(in(*cx) let transfer = UndefinedValue());
+        let data = StructuredCloneData::write(*cx, message, transfer.handle())?;
 
         // Step 9.
         self.post_message(origin, data);