Bug 1502802 - Implement PostMessageOptions for MessagePort, r=smaug

dom/messagechannel/MessagePort.cpp

@@ -411,6 +411,14 @@ MessagePort::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
   mActor->SendPostMessages(messages);
 }
 
+void
+MessagePort::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
+                         const PostMessageOptions& aOptions,
+                         ErrorResult& aRv)
+{
+  PostMessage(aCx, aMessage, aOptions.mTransfer, aRv);
+}
+
 void
 MessagePort::Start()
 {

dom/messagechannel/MessagePort.h

@@ -24,6 +24,7 @@ namespace dom {
 class ClonedMessageData;
 class MessagePortChild;
 class MessagePortIdentifier;
+struct PostMessageOptions;
 class PostMessageRunnable;
 class SharedMessagePortMessage;
 class StrongWorkerRef;
@@ -58,6 +59,11 @@ public:
               const Sequence<JSObject*>& aTransferable,
               ErrorResult& aRv);
 
+  void
+  PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
+              const PostMessageOptions& aOptions,
+              ErrorResult& aRv);
+
   void Start();
 
   void Close();

dom/webidl/MessagePort.webidl

@@ -10,7 +10,9 @@
 [Exposed=(Window,Worker,AudioWorklet)]
 interface MessagePort : EventTarget {
   [Throws]
-  void postMessage(any message, optional sequence<object> transferable = []);
+  void postMessage(any message, sequence<object> transferable);
+  [Throws]
+  void postMessage(any message, optional PostMessageOptions options);
 
   void start();
   void close();
@@ -20,3 +22,7 @@ interface MessagePort : EventTarget {
   attribute EventHandler onmessageerror;
 };
 // MessagePort implements Transferable;
+
+dictionary PostMessageOptions {
+  sequence<object> transfer = [];
+};

testing/web-platform/meta/webmessaging/message-channels/dictionary-transferrable.html.ini

@@ -1,4 +0,0 @@
-[dictionary-transferrable.html]
-  [basic messagechannel with transfer]
-    expected: FAIL
-