Bug 1339351 - fix typo. r=kaku

MozReview-Commit-ID: ApKvXMTqcDm

--HG--
extra : rebase_source : 6118ef0439cf2451f161bb491841e749e6eb1aab
extra : intermediate-source : de5851e330100048a2db2889b2f9cd3bf86ce3e0
extra : source : 0b0d7bf4fb45a64752b8703e0f6189cb93b1452b

dom/media/test/background_video.js

@@ -51,7 +51,7 @@ function waitUntilEnded(video) {
   Log(video.token, "Waiting for ended");
   if (video.ended) {
     ok(true, video.token + " already ended");
-    return Promise.success();
+    return Promise.resolve();
   }
 
   return once(video, 'ended', () => { ok(true, video.token + " ended"); });