Bug 1424948 - Use waitForNextFrame instead of waitForFrame. r=birtles

MozReview-Commit-ID: AZJ7LyeIKq2

--HG--
extra : rebase_source : f42d2b0d4220d3d458093fdc5aed7ff11dcff63e

dom/animation/test/css-transitions/file_animation-pausing.html

@@ -37,7 +37,7 @@ async_test(function(t) {
                   'margin-left does not increase after calling pause()');
     previousAnimVal = getMarginLeft(cs);
     animation.play();
-    return animation.ready.then(waitForFrame);
+    return animation.ready.then(waitForNextFrame);
   })).then(t.step_func(function() {
     assert_greater_than(getMarginLeft(cs), previousAnimVal,
                         'margin-left increases after calling play()');