Bug 1208328 - Test MediaStreamTrackEvent like RTCTrackEvent. r=smaug

MozReview-Commit-ID: GAEu2FskUJr

--HG--
extra : rebase_source : 3f31d212470e67bfb1e336d6215a301b2ca18a8c
extra : intermediate-source : 3160ce8f87590a3a611267595cb478479dfdb2f3
extra : source : ece1345d0b6558ff5358f906aad56f0f32648bcd

dom/events/test/test_all_synthetic_events.html

@@ -303,9 +303,8 @@ const kEventConstructors = {
                                                          return new MediaStreamEvent(aName, aProps);
                                                        },
                                              },
-  MediaStreamTrackEvent:                     { create: function (aName, aProps) {
-                                                         return new MediaStreamTrackEvent(aName, aProps);
-                                                       },
+  MediaStreamTrackEvent:                     {
+                                               // Difficult to test required arguments.
                                              },
   MessageEvent:                              { create: function (aName, aProps) {
                                                          var e = new MessageEvent("messageevent", { bubbles: aProps.bubbles,

dom/media/tests/mochitest/test_getUserMedia_addtrack_removetrack_events.html

@@ -97,6 +97,11 @@ runTest(() => getUserMedia({audio: true, video: true})
     stream.getTracks().forEach(t => removeTrack(t));
 
     return spinEventLoop();
+  })
+  .then(() => {
+      // Test MediaStreamTrackEvent required args here.
+      mustThrowWith("MediaStreamTrackEvent without required args",
+                    "TypeError", () => new MediaStreamTrackEvent("addtrack", {}));
   }));
 </script>
 </pre>