Convert track-webvtt-tc[016-018] tests to testharness.js

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

Index: third_party/WebKit/LayoutTests/media/track/track-helpers.js
diff --git a/third_party/WebKit/LayoutTests/media/track/track-helpers.js b/third_party/WebKit/LayoutTests/media/track/track-helpers.js
index f56e8240c4bade51ccc20a5c6806e313b732f08f..0e5db69461f06b2ae6e8442795cb30ee5599718f 100644
--- a/third_party/WebKit/LayoutTests/media/track/track-helpers.js
+++ b/third_party/WebKit/LayoutTests/media/track/track-helpers.js
@@ -14,4 +14,14 @@ function assert_cues_equal(cues, expected) {
         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)
+            assert_equals(cue[property], expectedItem[property]);
+    }
 }