--- a/layout/style/test/stylo-failures.md
+++ b/layout/style/test/stylo-failures.md
@@ -36,19 +36,16 @@ to mochitest command.
   * test_media_queries_dynamic.html `restyle`: bug 1357461 [4]
   * test_media_queries_dynamic_xbl.html: xbl support bug 1290276 [1]
 * Animation support:
   * SMIL Animation
     * test_restyles_in_smil_animation.html [2]
 * console support bug 1352669
   * test_bug413958.html `monitorConsole` [3]
   * test_parser_diagnostics_unprintables.html [550]
-* Transition support:
-  * Events:
-    * test_animations_event_order.html [2]
 * Unimplemented \@font-face descriptors:
   * test_font_face_parser.html `font-language-override`: bug 1355364 [8]
 * keyword values should be preserved in \@font-face bug 1355368
   * test_font_face_parser.html `font-weight` [4]
   * test_font_loading_api.html `weight` [1]
 * @namespace support:
   * test_namespace_rule.html: bug 1355715 [6]
 * test_font_feature_values_parsing.html: \@font-feature-values support bug 1355721 [107]

--- a/layout/style/test/test_animations_event_order.html
+++ b/layout/style/test/test_animations_event_order.html
@@ -623,18 +623,16 @@ checkEventOrder([ divs[0], 'transitionru
                 [ divs[0], 'transitionend' ],
                 'Simultaneous transitionrun/start/end on siblings');
 
 divs.forEach(div => div.remove());
 divs = [];
 
 // 4j. Test sorting transitions with cancel
 // The order of transitioncancel is based on StyleManager.
-// So this test looks like wrong result at a glance. However
-// the gecko will cancel div1's transition before div2 in this case.
 
 divs = [ document.createElement('div'),
          document.createElement('div') ];
 divs.forEach((div, i) => {
   gDisplay.appendChild(div);
   div.style.marginLeft = '0px';
   div.setAttribute('id', 'div' + i);
 });
@@ -643,26 +641,32 @@ divs[0].style.transition = 'margin-left 
 divs[1].style.transition = 'margin-left 10s';
 
 getComputedStyle(divs[0]).marginLeft;
 divs.forEach(div => div.style.marginLeft = '100px');
 getComputedStyle(divs[0]).marginLeft;
 
 advance_clock(0);
 advance_clock(5 * 1000);
-divs.forEach(div =>  div.style.display = 'none' );
-getComputedStyle(divs[0]).display;
+divs.forEach(div =>  {
+  div.style.display = 'none';
+  // The transitioncancel event order is not absolute when firing siblings
+  // transitioncancel on same elapsed time.
+  // Force to flush style for the element so that the transition on the element
+  // iscancelled and corresponding cancel event is queued respectively.
+  getComputedStyle(div).display;
+});
 advance_clock(10 * 1000);
 
 checkEventOrder([ divs[0], 'transitionrun' ],
                 [ divs[1], 'transitionrun' ],
                 [ divs[1], 'transitionstart' ],
                 [ divs[0], 'transitionstart' ],
+                [ divs[0], 'transitioncancel' ],
                 [ divs[1], 'transitioncancel' ],
-                [ divs[0], 'transitioncancel' ],
                 'Simultaneous transitionrun/start/cancel on siblings');
 
 divs.forEach(div => div.remove());
 divs = [];
 
 
 // 4k. Test sorting animations with cancel
 
@@ -677,23 +681,29 @@ divs.forEach((div, i) => {
 
 divs[0].style.animation = 'anim 10s 5s';
 divs[1].style.animation = 'anim 10s';
 
 getComputedStyle(divs[0]).animation; // flush
 
 advance_clock(0);  // divs[1]'s animation start
 advance_clock(5 * 1000);  // divs[0]'s animation start
-divs.forEach(div => div.style.display = 'none' );
-getComputedStyle(divs[0]).display;
+divs.forEach(div => {
+  div.style.display = 'none';
+  // The animationcancel event order is not absolute when firing siblings
+  // animationcancel on same elapsed time.
+  // Force to flush style for the element so that the transition on the element
+  // iscancelled and corresponding cancel event is queued respectively.
+  getComputedStyle(div).display;
+});
 advance_clock(10 * 1000);
 
 checkEventOrder([ divs[1], 'animationstart' ],
                 [ divs[0], 'animationstart' ],
+                [ divs[0], 'animationcancel' ],
                 [ divs[1], 'animationcancel' ],
-                [ divs[0], 'animationcancel' ],
                 'Simultaneous animationcancel on siblings');
 
 SpecialPowers.DOMWindowUtils.restoreNormalRefresh();
 
 </script>
 </body>
 </html>