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/abstractworkerglobalscope.rs

@@ -75,7 +75,7 @@ impl ScriptPort for Receiver<DedicatedWorkerScriptMsg> {
         };
         match common_msg {
             WorkerScriptMsg::Common(script_msg) => Ok(script_msg),
-            WorkerScriptMsg::DOMMessage(_) => panic!("unexpected worker event message!"),
+            WorkerScriptMsg::DOMMessage { .. } => panic!("unexpected worker event message!"),
         }
     }
 }