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/task_source/mod.rs

@@ -8,6 +8,7 @@ pub mod history_traversal;
 pub mod media_element;
 pub mod networking;
 pub mod performance_timeline;
+pub mod port_message;
 pub mod remote_event;
 pub mod user_interaction;
 pub mod websocket;
@@ -28,6 +29,7 @@ pub enum TaskSourceName {
     HistoryTraversal,
     Networking,
     PerformanceTimeline,
+    PortMessage,
     UserInteraction,
     RemoteEvent,
     MediaElement,