--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -207833,17 +207833,17 @@
    "53a4a6c6c6d07e00fecc50e5de831862e7bf4b2e",
    "testharness"
   ],
   "web-animations/timing-model/animations/current-time.html": [
    "b1ea8e490cbfb69fd71b91a90e7e2d9ce99f42d3",
    "testharness"
   ],
   "web-animations/timing-model/animations/reversing-an-animation.html": [
-   "80327fe9a7c68d280b7b4cfba42d081358ee1ea7",
+   "2b5631893d0d0846e5e57097ce4ae54dfa8a03e3",
    "testharness"
   ],
   "web-animations/timing-model/animations/set-the-animation-start-time.html": [
    "84afa495b1a4c467e27b1394f6449a18c58ed98d",
    "testharness"
   ],
   "web-animations/timing-model/animations/set-the-target-effect-of-an-animation.html": [
    "840be610db4bce6d6fd1c22710e494a75ee95eba",

--- a/testing/web-platform/tests/web-animations/timing-model/animations/reversing-an-animation.html
+++ b/testing/web-platform/tests/web-animations/timing-model/animations/reversing-an-animation.html
@@ -53,16 +53,44 @@ test(function(t) {
 
   assert_equals(animation.currentTime, 50 * MS_PER_SEC,
     'The current time should not change it is in the middle of ' +
     'the animation duration');
 }, 'Reversing an animation maintains the same current time');
 
 test(function(t) {
   var div = createDiv(t);
+  var animation = div.animate({}, { duration: 200 * MS_PER_SEC,
+                                    delay: -100 * MS_PER_SEC });
+  assert_equals(animation.playState, 'pending',
+    'The playState is pending before we call reverse');
+
+  animation.reverse();
+
+  assert_equals(animation.playState, 'pending',
+    'The playState is still pending after calling reverse');
+}, 'Reversing an animation does not cause it to leave the pending state');
+
+promise_test(function(t) {
+  var div = createDiv(t);
+  var animation = div.animate({}, { duration: 200 * MS_PER_SEC,
+                                    delay: -100 * MS_PER_SEC });
+  var readyResolved = false;
+  animation.ready.then(() => { readyResolved = true; });
+
+  animation.reverse();
+
+  return Promise.resolve(() => {
+    assert_false(readyResolved,
+                 'ready promise should not have been resolved yet');
+  });
+}, 'Reversing an animation does not cause it to resolve the ready promise');
+
+test(function(t) {
+  var div = createDiv(t);
   var animation = div.animate({}, 100 * MS_PER_SEC);
   animation.currentTime = 200 * MS_PER_SEC;
   animation.reverse();
 
   assert_equals(animation.currentTime, 100 * MS_PER_SEC,
     'reverse() should start playing from the animation effect end ' +
     'if the playbackRate > 0 and the currentTime > effect end');
 }, 'Reversing an animation when playbackRate > 0 and currentTime > ' +