diff --git a/dom/animation/test/chrome/test_animation_observers.html b/dom/animation/test/chrome/test_animation_observers.html
index d914c0a3a606..33a690b51c06 100644
--- a/dom/animation/test/chrome/test_animation_observers.html
+++ b/dom/animation/test/chrome/test_animation_observers.html
@@ -1511,6 +1511,43 @@ addAsyncAnimTest("change_duration_and_currenttime",
   yield await_frame();
 });
 
+addAsyncAnimTest("change_enddelay_and_currenttime",
+                 { observe: div, subtree: true }, function*() {
+  var anim = div.animate({ opacity: [ 0, 1 ] }, { duration: 100000 });
+  yield await_frame();
+  assert_records([{ added: [anim], changed: [], removed: [] }],
+                 "records after animation is added");
+
+  anim.effect.timing.endDelay = 10000;
+  yield await_frame();
+  assert_records([{ added: [], changed: [anim], removed: [] }],
+                 "records after endDelay is changed");
+
+  anim.effect.timing.endDelay = 10000;
+  yield await_frame();
+  assert_records([], "records after assigning same value");
+
+  anim.currentTime = 109000;
+  yield await_frame();
+  assert_records([{ added: [], changed: [], removed: [anim] }],
+                 "records after currentTime during endDelay");
+
+  anim.effect.timing.endDelay = -110000;
+  yield await_frame();
+  assert_records([], "records after assigning negative value");
+
+  anim.cancel();
+  yield await_frame();
+});
+
+addAsyncAnimTest("change_enddelay_and_currenttime",
+                 { observe: div, subtree: true }, function*() {
+  var anim = div.animate({ opacity: [ 0, 1 ] },
+                         { duration: 100, endDelay: -100 });
+  yield await_frame();
+  assert_records([], "records after animation is added");
+});
+
 // Run the tests.
 SimpleTest.requestLongerTimeout(2);
 SimpleTest.waitForExplicitFinish();
diff --git a/dom/animation/test/chrome/test_running_on_compositor.html b/dom/animation/test/chrome/test_running_on_compositor.html
index 75edff3641e5..688e24137a29 100644
--- a/dom/animation/test/chrome/test_running_on_compositor.html
+++ b/dom/animation/test/chrome/test_running_on_compositor.html
@@ -327,6 +327,72 @@ promise_test(function(t) {
 }, 'animation is added to compositor' +
    ' when timing.duration is made longer than the current time');
 
+promise_test(function(t) {
+  var div = addDiv(t);
+  var animation = div.animate({ opacity: [ 0, 1 ] }, 10000);
+
+  return animation.ready.then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, omtaEnabled,
+      'Animation reports that it is running on the compositor');
+
+    animation.effect.timing.endDelay = 10000;
+
+    assert_equals(animation.isRunningOnCompositor, omtaEnabled,
+      'Animation reports that it is running on the compositor'
+      + ' when endDelay is changed');
+
+    animation.currentTime = 11000;
+    return waitForFrame();
+  })).then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, false,
+      'Animation reports that it is NOT running on the compositor'
+      + ' when currentTime is during endDelay');
+  }));
+}, 'animation is removed from compositor' +
+   ' when current time is made longer than the duration even during endDelay');
+
+promise_test(function(t) {
+  var div = addDiv(t);
+  var animation = div.animate({ opacity: [ 0, 1 ] }, 10000);
+
+  return animation.ready.then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, omtaEnabled,
+      'Animation reports that it is running on the compositor');
+
+    animation.effect.timing.endDelay = -20000;
+    return waitForFrame();
+  })).then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, false,
+      'Animation reports that it is NOT running on the compositor'
+      + ' when endTime is negative value');
+  }));
+}, 'animation is removed from compositor' +
+   ' when endTime is negative value');
+
+promise_test(function(t) {
+  var div = addDiv(t);
+  var animation = div.animate({ opacity: [ 0, 1 ] }, 10000);
+
+  return animation.ready.then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, omtaEnabled,
+      'Animation reports that it is running on the compositor');
+
+    animation.effect.timing.endDelay = -5000;
+    return waitForFrame();
+  })).then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, omtaEnabled,
+      'Animation reports that it is running on the compositor'
+      + ' when endTime is positive and endDelay is negative');
+    animation.currentTime = 6000;
+    return waitForFrame();
+  })).then(t.step_func(function() {
+    assert_equals(animation.isRunningOnCompositor, false,
+      'Animation reports that it is NOT running on the compositor'
+      + ' when currentTime is after endTime');
+  }));
+}, 'animation is NOT running on compositor' +
+   'when endTime is positive and endDelay is negative');
+
 </script>
 </script>
 </body>