--- a/dom/media/mediasource/test/test_BufferingWait.html
+++ b/dom/media/mediasource/test/test_BufferingWait.html
@@ -15,46 +15,33 @@ var receivedSourceOpen = false;
 runWithMSE(function(ms, v) {
   ms.addEventListener("sourceopen", function() {
     ok(true, "Receive a sourceopen event");
     ok(!receivedSourceOpen, "Should only receive one sourceopen for this test");
     receivedSourceOpen = true;
     var sb = ms.addSourceBuffer("video/webm");
     ok(sb, "Create a SourceBuffer");
 
-    function waitUntilTime(targetTime) {
-      return new Promise(function(resolve, reject) {
-        v.addEventListener("waiting", function onwaiting() {
-          info("Got a waiting event at " + v.currentTime);
-          if (v.currentTime >= targetTime) {
-            ok(true, "Reached target time of: " + targetTime);
-            v.removeEventListener("waiting", onwaiting);
-            resolve();
-          }
-        });
-      });
-    }
-
     fetchWithXHR("seek.webm", function(arrayBuffer) {
       sb.addEventListener('error', (e) => { ok(false, "Got Error: " + e); SimpleTest.finish(); });
       loadSegment.bind(null, sb, new Uint8Array(arrayBuffer, 0, 318))().then(
       loadSegment.bind(null, sb, new Uint8Array(arrayBuffer, 318, 25523-318))).then(
       loadSegment.bind(null, sb, new Uint8Array(arrayBuffer, 25523, 46712-25523))).then(
       /* Note - Missing |46712, 67833 - 46712| segment here corresponding to (0.8, 1.2] */
       /* Note - Missing |67833, 88966 - 67833| segment here corresponding to (1.2, 1.6]  */
       loadSegment.bind(null, sb, new Uint8Array(arrayBuffer, 88966))).then(function() {
         // 0.767 is the time of the last video sample +- 40ms.
-        var promise = waitUntilTime(.767-0.04);
+        var promise = waitUntilTime(v, .767-0.04);
         info("Playing video. It should play for a bit, then fire 'waiting'");
         v.play();
         return promise;
       }).then(function() {
         window.firstStop = Date.now();
         loadSegment(sb, new Uint8Array(arrayBuffer, 46712, 67833 - 46712));
-        return waitUntilTime(1.167-0.04);
+        return waitUntilTime(v, 1.167-0.04);
       }).then(function() {
         var waitDuration = (Date.now() - window.firstStop) / 1000;
         ok(waitDuration < 15, "Should not spend an inordinate amount of time buffering: " + waitDuration);
         SimpleTest.finish();
         /* If we allow the rest of the stream to be played, we get stuck at
            around 2s. See bug 1093133.
         once(v, 'ended', SimpleTest.finish.bind(SimpleTest));
         return loadSegment(sb, new Uint8Array(arrayBuffer, 67833, 88966 - 67833));

--- a/dom/media/mediasource/test/test_BufferingWait_mp4.html
+++ b/dom/media/mediasource/test/test_BufferingWait_mp4.html
@@ -15,47 +15,34 @@ var receivedSourceOpen = false;
 runWithMSE(function(ms, v) {
   ms.addEventListener("sourceopen", function() {
     ok(true, "Receive a sourceopen event");
     ok(!receivedSourceOpen, "Should only receive one sourceopen for this test");
     receivedSourceOpen = true;
     var sb = ms.addSourceBuffer("video/mp4");
     ok(sb, "Create a SourceBuffer");
 
-    function waitUntilTime(targetTime) {
-      return new Promise(function(resolve, reject) {
-        v.addEventListener("waiting", function onwaiting() {
-          info("Got a waiting event at " + v.currentTime);
-          if (v.currentTime >= targetTime) {
-            ok(true, "Reached target time of: " + targetTime);
-            v.removeEventListener("waiting", onwaiting);
-            resolve();
-          }
-        });
-      });
-    }
-
     sb.addEventListener('error', (e) => { ok(false, "Got Error: " + e); SimpleTest.finish(); });
     fetchAndLoad(sb, 'bipbop/bipbop', ['init'], '.mp4')
     .then(fetchAndLoad.bind(null, sb, 'bipbop/bipbop', ['1'], '.m4s'))
     .then(fetchAndLoad.bind(null, sb, 'bipbop/bipbop', ['2'], '.m4s'))
     /* Note - Missing |bipbop3| segment here corresponding to (1.62, 2.41] */
     /* Note - Missing |bipbop4| segment here corresponding to (2.41, 3.20]  */
     .then(fetchAndLoad.bind(null, sb, 'bipbop/bipbop', ['5'], '.m4s'))
     .then(function() {
         // last audio sample has a start time of 1.578956s
-        var promise = waitUntilTime(1.57895);
+        var promise = waitUntilTime(v, 1.57895);
         info("Playing video. It should play for a bit, then fire 'waiting'");
         v.play();
         return promise;
       }).then(function() {
         window.firstStop = Date.now();
         fetchAndLoad(sb, 'bipbop/bipbop', ['3'], '.m4s');
         // last audio sample has a start time of 2.368435
-        return waitUntilTime(2.36843);
+        return waitUntilTime(v, 2.36843);
       }).then(function() {
         var waitDuration = (Date.now() - window.firstStop) / 1000;
         ok(waitDuration < 15, "Should not spend an inordinate amount of time buffering: " + waitDuration);
         once(v, 'ended', SimpleTest.finish.bind(SimpleTest));
         return fetchAndLoad(sb, 'bipbop/bipbop', ['4'], '.m4s');
       }).then(function() {
         ms.endOfStream();
       });;