--- a/dom/animation/test/css-animations/test_animation-ready.html
+++ b/dom/animation/test/css-animations/test_animation-ready.html
@@ -36,23 +36,18 @@ promise_test(async t => {
   const animation = div.getAnimations()[0];
   assert_true(animation.pending, 'Animation is initially pending');
   const readyPromise = animation.ready;
 
   // Cancel the animation and flush styles
   div.style.animation = '';
   getComputedStyle(div).animation;
 
-  try {
-    await readyPromise;
-    assert_unreached('ready promise is fulfilled');
-  } catch(err) {
-    assert_equals(err.name, 'AbortError',
-                  'ready promise is rejected with AbortError');
-  }
+  await promise_rejects(t, 'AbortError', readyPromise,
+                        'ready promise is rejected with AbortError');
 }, 'ready promise is rejected when an animation is canceled by resetting'
    + ' the animation property');
 
 promise_test(async t => {
   const div = addDiv(t);
 
   // As before, but this time instead of removing all animations, simply update
   // the list of animations. At least for Firefox, updating is a different
@@ -63,23 +58,18 @@ promise_test(async t => {
   const animation = div.getAnimations()[0];
   assert_true(animation.pending, 'Animation is initially pending');
   const readyPromise = animation.ready;
 
   // Update the animation and flush styles
   div.style.animation = 'def 100s';
   getComputedStyle(div).animation;
 
-  try {
-    await readyPromise;
-    assert_unreached('ready promise is fulfilled');
-  } catch(err) {
-    assert_equals(err.name, 'AbortError',
-                  'ready promise is rejected with AbortError');
-  }
+  await promise_rejects(t, 'AbortError', readyPromise,
+                        'ready promise is rejected with AbortError');
 }, 'ready promise is rejected when an animation is canceled by updating'
    + ' the animation property');
 
 promise_test(async t => {
   const div = addDiv(t, { style: 'animation: abc 100s' });
   const animation = div.getAnimations()[0];
   const originalReadyPromise = animation.ready;
 
@@ -99,51 +89,10 @@ promise_test(async t => {
 
   div.style.animationPlayState = 'paused';
   const firstReadyPromise = animation.ready;
   animation.pause();
   assert_equals(animation.ready, firstReadyPromise,
                 'Ready promise objects are identical after redundant pause');
 }, 'Pausing twice re-uses the same Promise');
 
-promise_test(async t => {
-  const div = addDiv(t, { style: 'animation: abc 100s' });
-  const animation = div.getAnimations()[0];
-
-  await animation.ready;
-
-  div.style.animationPlayState = 'paused';
-
-  // Flush style and verify we're pending at the same time
-  assert_true(animation.pending, 'Animation is pending');
-  const pauseReadyPromise = animation.ready;
-
-  // Now play again immediately
-  div.style.animationPlayState = 'running';
-  assert_true(animation.pending, 'Animation is still pending');
-  assert_equals(animation.ready, pauseReadyPromise,
-                'The pause Promise is re-used when playing while waiting'
-                + ' to pause');
-
-  await animation.ready;
-
-  assert_true(!animation.pending && animation.playState === 'running',
-              'Animation is running after aborting a pause');
-}, 'If a pause operation is interrupted, the ready promise is reused');
-
-promise_test(async t => {
-  const div = addDiv(t, { style: 'animation: abc 100s' });
-  const animation = div.getAnimations()[0];
-
-  await animation.ready;
-
-  div.style.animationPlayState = 'paused';
-
-  const resolvedAnimation = await animation.ready;
-
-  assert_equals(resolvedAnimation, animation,
-                'Promise received when ready Promise for a pause operation'
-                + ' is completed is the animation on which the pause was'
-                + ' performed');
-}, 'When a pause is complete the Promise callback gets the correct animation');
-
 </script>
 </body>

--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -615892,17 +615892,17 @@
    "27e4132548fc430fae19f3bab9cc8dc8c5a263ca",
    "testharness"
   ],
   "web-animations/timing-model/animations/play-states.html": [
    "0ab2fa3a464001272d1af541ea769fa967490c3b",
    "testharness"
   ],
   "web-animations/timing-model/animations/playing-an-animation.html": [
-   "386ed5ae920f51b80b9f7dc3a0fdf4526081817f",
+   "f6c36cc2370b08037e5a99009e6def67df84a4a7",
    "testharness"
   ],
   "web-animations/timing-model/animations/reversing-an-animation.html": [
    "72b89e78ca7dac261af8de370389d89c810b3718",
    "testharness"
   ],
   "web-animations/timing-model/animations/seamlessly-updating-the-playback-rate-of-an-animation.html": [
    "a7e28aa0b40a39b00da257e347cb6ecf8d1d2882",

--- a/testing/web-platform/tests/web-animations/timing-model/animations/playing-an-animation.html
+++ b/testing/web-platform/tests/web-animations/timing-model/animations/playing-an-animation.html
@@ -67,16 +67,38 @@ promise_test(async t => {
   const promise = animation.ready;
   const promiseResult = await promise;
   assert_equals(promiseResult, animation);
   assert_equals(animation.ready, promise);
 }, 'A pending ready promise should be resolved and not replaced when the'
    + ' animation enters the running state');
 
 promise_test(async t => {
+  const animation = createDiv(t).animate(null, 100 * MS_PER_SEC);
+  await animation.ready;
+
+  // Go to pause-pending state
+  animation.pause();
+  assert_true(animation.pending, 'Animation is pending');
+  const pauseReadyPromise = animation.ready;
+
+  // Now play again immediately (abort the pause)
+  animation.play();
+  assert_true(animation.pending, 'Animation is still pending');
+  assert_equals(animation.ready, pauseReadyPromise,
+                'The pause Promise is re-used when playing while waiting'
+                + ' to pause');
+
+  // Sanity check: Animation proceeds to running state
+  await animation.ready;
+  assert_true(!animation.pending && animation.playState === 'running',
+              'Animation is running after aborting a pause');
+}, 'If a pause operation is interrupted, the ready promise is reused');
+
+promise_test(async t => {
   // Seek animation beyond target end
   const animation = createDiv(t).animate(null, 100 * MS_PER_SEC);
   animation.currentTime = -100 * MS_PER_SEC;
   await animation.ready;
 
   // Set pending playback rate to the opposite direction
   animation.updatePlaybackRate(-1);
   assert_true(animation.pending);