Convert track-webvtt-tc[019-021] tests to testharness.js

third_party/WebKit/LayoutTests/media/track/track-helpers.js

 function enableAllTextTracks(textTracks) {
     for (var i = 0; i < textTracks.length; i++) {
         var track = textTracks[i];
         if (track.mode == "disabled")
             track.mode = "hidden";
     }
 }
 
 function assert_cues_equal(cues, expected) {
     assert_equals(cues.length, expected.length);
     for (var i = 0; i < cues.length; i++) {
         assert_equals(cues[i].id, expected[i].id);
         assert_equals(cues[i].startTime, expected[i].startTime);
         assert_equals(cues[i].endTime, expected[i].endTime);
         assert_equals(cues[i].text, expected[i].text);
     }
 }
 
 function assert_cues_match(cues, expected, properties) {
     assert_equals(cues.length, expected.length);
     for (var i = 0; i < cues.length; i++) {
         var cue = cues[i];
         var expectedItem = expected[i];
         for (var property of properties)

[foolip, 2016/06/02 09:14:18]

Is the properties array really needed? Can't this use
Object.getOwnPropertyNames(expected) instead? At the call sites it looks a bit
redundant.

[fs, 2016/06/02 09:32:46]

Yes, that ought to work (with s/expected/expectedItem/ presumably.)

[Srirama, 2016/06/02 09:59:27]

Done.

             assert_equals(cue[property], expectedItem[property]);
     }
+}
+
+function check_cues_from_track(src, func) {
+    async_test(function(t) {
+        var video = document.createElement("video");
+        var trackElement = document.createElement("track");
+        trackElement.src = src;
+        trackElement.default = true;
+        video.appendChild(trackElement);
+
+        trackElement.onload = t.step_func_done(function() {
+            func(trackElement.track);
+        });
+    }, "Check cues from " + src);
 }