Bug 1458414 - Enable test_animation_omta.html on WebRender. r=kats

But some test cases are skipped, they will be enabled in bug 1456679.

MozReview-Commit-ID: HLxPjkf6KjY

--HG--
extra : rebase_source : 55c24d34a53423a921060a431ac941b068407eb9

layout/style/test/mochitest.ini

@@ -58,7 +58,6 @@ support-files = Ahem.ttf file_animations_async_tests.html
 [test_animations_event_handler_attribute.html]
 [test_animations_iterationstart.html]
 [test_animations_omta.html]
-skip-if = webrender # bug 1424752
 [test_animations_omta_start.html]
 [test_animations_pausing.html]
 [test_animations_playbackrate.html]

layout/style/test/test_animations_omta.html

@@ -181,6 +181,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=964646
 <script type="application/javascript">
 "use strict";
 
+const isWebRender =
+  SpecialPowers.DOMWindowUtils.layerManagerType == 'WebRender';
+
 /** Test for css3-animations running on the compositor thread (Bug 964646) **/
  
 // Global state
@@ -337,9 +340,13 @@ async function testFillMode(fillMode, fillsBackwards, fillsForwards)
   done_div();
 }
 
-addAsyncAnimTest(function() { return testFillMode("", false, false); });
-addAsyncAnimTest(function() { return testFillMode("none", false, false); });
-addAsyncAnimTest(function() { return testFillMode("forwards", false, true); });
+// FIXME: Bug 1456679: On WebRender these test cases incorrectly get style value
+// on the compositor when the animation is in-delay phase.
+if (!isWebRender) {
+  addAsyncAnimTest(function() { return testFillMode("", false, false); });
+  addAsyncAnimTest(function() { return testFillMode("none", false, false); });
+  addAsyncAnimTest(function() { return testFillMode("forwards", false, true); });
+}
 addAsyncAnimTest(function() { return testFillMode("backwards", true, false); });
 addAsyncAnimTest(function() { return testFillMode("both", true, true); });