Adds support to accept transfers in sink.enqueue method.

src/shared/util.js

@@ -1433,13 +1433,19 @@ MessageHandler.prototype = {
     let targetName = data.sourceName;
     let capability = createPromiseCapability();
 
-    let sendStreamRequest = ({ stream, chunk, success, reason, }) => {
+    let sendStreamRequest = ({ stream, chunk, transfers,
+                               success, reason, }) => {
+      if (transfers) {
+        this.postMessage({ sourceName, targetName, stream, streamId,
+                           chunk, success, reason, }, transfers);
+        return;
+      }
       this.comObj.postMessage({ sourceName, targetName, stream, streamId,
                                 chunk, success, reason, });
     };
 
     let streamSink = {
-      enqueue(chunk, size = 1) {
+      enqueue(chunk, size = 1, transfers) {
         let lastDesiredSize = this.desiredSize;
         this.desiredSize -= size;
         // Enqueue decreases the desiredSize property of sink,
@@ -1449,7 +1455,7 @@ MessageHandler.prototype = {
           this.sinkCapability = createPromiseCapability();
           this.ready = this.sinkCapability.promise;
         }
-        sendStreamRequest({ stream: 'enqueue', chunk, });
+        sendStreamRequest({ stream: 'enqueue', chunk, transfers, });
       },
 
       close() {