Bug 1264125: Fire transitioncancel event when a transition is canceled (added tests + style clean up)

Issue #55

9 files changed, 679 insertions, 287 deletions

diff --git a/dom/animation/ComputedTiming.h b/dom/animation/ComputedTiming.h
index 525d59d23..b1c6674a5 100644
--- a/dom/animation/ComputedTiming.h
+++ b/dom/animation/ComputedTiming.h
@@ -30,7 +30,7 @@ struct ComputedTiming
   // indefinitely.
   StickyTimeDuration  mActiveDuration;
   // The time within the active interval.
-  StickyTimeDuration mActiveTime;
+  StickyTimeDuration  mActiveTime;
   // The effect end time in local time (i.e. an offset from the effect's
   // start time). Will equal StickyTimeDuration::Forever() if the animation
   // plays indefinitely.
diff --git a/dom/animation/test/css-transitions/file_animation-cancel.html b/dom/animation/test/css-transitions/file_animation-cancel.html
index 6094b383f..71f02fb11 100644
--- a/dom/animation/test/css-transitions/file_animation-cancel.html
+++ b/dom/animation/test/css-transitions/file_animation-cancel.html
@@ -11,13 +11,12 @@ promise_test(function(t) {
 
   div.style.transition = 'margin-left 100s';
   div.style.marginLeft = '1000px';
-  flushComputedStyle(div);
 
-  var animation = div.getAnimations()[0];
-  return animation.ready.then(waitForFrame).then(function() {
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(waitForFrame).then(function() {
     assert_not_equals(getComputedStyle(div).marginLeft, '1000px',
                       'transform style is animated before cancelling');
-    animation.cancel();
+    transition.cancel();
     assert_equals(getComputedStyle(div).marginLeft, div.style.marginLeft,
                   'transform style is no longer animated after cancelling');
   });
@@ -29,45 +28,21 @@ promise_test(function(t) {
 
   div.style.transition = 'margin-left 100s';
   div.style.marginLeft = '1000px';
-  flushComputedStyle(div);
-
-  div.addEventListener('transitionend', function() {
-    assert_unreached('Got unexpected end event on cancelled transition');
-  });
-
-  var animation = div.getAnimations()[0];
-  return animation.ready.then(function() {
-    // Seek to just before the end then cancel
-    animation.currentTime = 99.9 * 1000;
-    animation.cancel();
 
-    // Then wait a couple of frames and check that no event was dispatched
-    return waitForAnimationFrames(2);
-  });
-}, 'Cancelled CSS transitions do not dispatch events');
-
-promise_test(function(t) {
-  var div = addDiv(t, { style: 'margin-left: 0px' });
-  flushComputedStyle(div);
-
-  div.style.transition = 'margin-left 100s';
-  div.style.marginLeft = '1000px';
-  flushComputedStyle(div);
-
-  var animation = div.getAnimations()[0];
-  return animation.ready.then(function() {
-    animation.cancel();
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    transition.cancel();
     assert_equals(getComputedStyle(div).marginLeft, '1000px',
                   'margin-left style is not animated after cancelling');
-    animation.play();
+    transition.play();
     assert_equals(getComputedStyle(div).marginLeft, '0px',
                   'margin-left style is animated after re-starting transition');
-    return animation.ready;
+    return transition.ready;
   }).then(function() {
-    assert_equals(animation.playState, 'running',
+    assert_equals(transition.playState, 'running',
                   'Transition succeeds in running after being re-started');
   });
-}, 'After cancelling a transition, it can still be re-used');
+}, 'After canceling a transition, it can still be re-used');
 
 promise_test(function(t) {
   var div = addDiv(t, { style: 'margin-left: 0px' });
@@ -75,20 +50,19 @@ promise_test(function(t) {
 
   div.style.transition = 'margin-left 100s';
   div.style.marginLeft = '1000px';
-  flushComputedStyle(div);
 
-  var animation = div.getAnimations()[0];
-  return animation.ready.then(function() {
-    animation.finish();
-    animation.cancel();
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    transition.finish();
+    transition.cancel();
     assert_equals(getComputedStyle(div).marginLeft, '1000px',
                   'margin-left style is not animated after cancelling');
-    animation.play();
+    transition.play();
     assert_equals(getComputedStyle(div).marginLeft, '0px',
                   'margin-left style is animated after re-starting transition');
-    return animation.ready;
+    return transition.ready;
   }).then(function() {
-    assert_equals(animation.playState, 'running',
+    assert_equals(transition.playState, 'running',
                   'Transition succeeds in running after being re-started');
   });
 }, 'After cancelling a finished transition, it can still be re-used');
@@ -99,10 +73,9 @@ test(function(t) {
 
   div.style.transition = 'margin-left 100s';
   div.style.marginLeft = '1000px';
-  flushComputedStyle(div);
 
-  var animation = div.getAnimations()[0];
-  animation.cancel();
+  var transition = div.getAnimations()[0];
+  transition.cancel();
   assert_equals(getComputedStyle(div).marginLeft, '1000px',
                 'margin-left style is not animated after cancelling');
 
@@ -113,7 +86,7 @@ test(function(t) {
   assert_equals(getComputedStyle(div).marginLeft, '1000px',
                 'margin-left style is still not animated after updating'
                 + ' transition-duration');
-  assert_equals(animation.playState, 'idle',
+  assert_equals(transition.playState, 'idle',
                 'Transition is still idle after updating transition-duration');
 }, 'After cancelling a transition, updating transition properties doesn\'t make'
    + ' it live again');
@@ -124,15 +97,14 @@ promise_test(function(t) {
 
   div.style.transition = 'margin-left 100s';
   div.style.marginLeft = '1000px';
-  flushComputedStyle(div);
 
-  var animation = div.getAnimations()[0];
-  return animation.ready.then(function() {
-    assert_equals(animation.playState, 'running');
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
     div.style.display = 'none';
     return waitForFrame();
   }).then(function() {
-    assert_equals(animation.playState, 'idle');
+    assert_equals(transition.playState, 'idle');
     assert_equals(getComputedStyle(div).marginLeft, '1000px');
   });
 }, 'Setting display:none on an element cancels its transitions');
@@ -147,19 +119,115 @@ promise_test(function(t) {
 
   childDiv.style.transition = 'margin-left 100s';
   childDiv.style.marginLeft = '1000px';
-  flushComputedStyle(childDiv);
 
-  var animation = childDiv.getAnimations()[0];
-  return animation.ready.then(function() {
-    assert_equals(animation.playState, 'running');
+  var transition = childDiv.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
     parentDiv.style.display = 'none';
     return waitForFrame();
   }).then(function() {
-    assert_equals(animation.playState, 'idle');
+    assert_equals(transition.playState, 'idle');
     assert_equals(getComputedStyle(childDiv).marginLeft, '1000px');
   });
 }, 'Setting display:none cancels transitions on a child element');
 
+promise_test(function(t) {
+  var div = addDiv(t, { style: 'margin-left: 0px' });
+  flushComputedStyle(div);
+
+  div.style.transition = 'margin-left 100s';
+  div.style.marginLeft = '1000px';
+
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
+    // Set an unrecognized property value
+    div.style.transitionProperty = 'none';
+    flushComputedStyle(div);
+    return waitForFrame();
+  }).then(function() {
+    assert_equals(transition.playState, 'idle');
+    assert_equals(getComputedStyle(div).marginLeft, '1000px');
+  });
+}, 'Removing a property from transition-property cancels transitions on that '+
+   'property');
+
+promise_test(function(t) {
+  var div = addDiv(t, { style: 'margin-left: 0px' });
+  flushComputedStyle(div);
+
+  div.style.transition = 'margin-left 100s';
+  div.style.marginLeft = '1000px';
+
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
+    div.style.transition = 'margin-top 10s -10s'; // combined duration is zero
+    flushComputedStyle(div);
+    return waitForFrame();
+  }).then(function() {
+    assert_equals(transition.playState, 'idle');
+    assert_equals(getComputedStyle(div).marginLeft, '1000px');
+  });
+}, 'Setting zero combined duration');
+
+promise_test(function(t) {
+  var div = addDiv(t, { style: 'margin-left: 0px' });
+  flushComputedStyle(div);
+
+  div.style.transition = 'margin-left 100s';
+  div.style.marginLeft = '1000px';
+
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
+    div.style.marginLeft = '2000px';
+    flushComputedStyle(div);
+    return waitForFrame();
+  }).then(function() {
+    assert_equals(transition.playState, 'idle');
+  });
+}, 'Changing style to another interpolable value cancels the original ' +
+   'transition');
+
+promise_test(function(t) {
+  var div = addDiv(t, { style: 'margin-left: 0px' });
+  flushComputedStyle(div);
+
+  div.style.transition = 'margin-left 100s';
+  div.style.marginLeft = '1000px';
+
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
+    div.style.marginLeft = 'auto';
+    flushComputedStyle(div);
+    return waitForFrame();
+  }).then(function() {
+    assert_equals(div.getAnimations().length, 0,
+                  'There should be no transitions');
+    assert_equals(transition.playState, 'idle');
+  });
+}, 'An after-change style value can\'t be interpolated');
+
+promise_test(function(t) {
+  var div = addDiv(t, { style: 'margin-left: 0px' });
+  flushComputedStyle(div);
+
+  div.style.transition = 'margin-left 100s';
+  div.style.marginLeft = '1000px';
+
+  var transition = div.getAnimations()[0];
+  return transition.ready.then(function() {
+    assert_equals(transition.playState, 'running');
+    div.style.marginLeft = '0px';
+    flushComputedStyle(div);
+    return waitForFrame();
+  }).then(function() {
+    assert_equals(transition.playState, 'idle');
+  });
+}, 'Reversing a running transition cancels the original transition');
+
 done();
 </script>
 </body>
diff --git a/dom/animation/test/css-transitions/file_csstransition-events.html b/dom/animation/test/css-transitions/file_csstransition-events.html
deleted file mode 100644
index 5011bc130..000000000
--- a/dom/animation/test/css-transitions/file_csstransition-events.html
+++ /dev/null
@@ -1,223 +0,0 @@
-<!doctype html>
-<meta charset=utf-8>
-<title>Tests for CSS-Transition events</title>
-<link rel="help" href="https://drafts.csswg.org/css-transitions-2/#transition-events">
-<script src="../testcommon.js"></script>
-<body>
-<script>
-'use strict';
-
-/**
- * Helper class to record the elapsedTime member of each event.
- * The EventWatcher class in testharness.js allows us to wait on
- * multiple events in a certain order but only records the event
- * parameters of the most recent event.
- */
-function TransitionEventHandler(target) {
-  this.target = target;
-  this.target.ontransitionrun = function(evt) {
-    this.transitionrun = evt.elapsedTime;
-  }.bind(this);
-  this.target.ontransitionstart = function(evt) {
-    this.transitionstart = evt.elapsedTime;
-  }.bind(this);
-  this.target.ontransitionend = function(evt) {
-    this.transitionend = evt.elapsedTime;
-  }.bind(this);
-}
-
-TransitionEventHandler.prototype.clear = function() {
-  this.transitionrun   = undefined;
-  this.transitionstart = undefined;
-  this.transitionend   = undefined;
-};
-
-function setupTransition(t, transitionStyle) {
-  var div, watcher, handler, transition;
-  transitionStyle = transitionStyle || 'transition: margin-left 100s 100s';
-  div = addDiv(t, { style: transitionStyle });
-  watcher = new EventWatcher(t, div, [ 'transitionrun',
-                                       'transitionstart',
-                                       'transitionend' ]);
-  handler = new TransitionEventHandler(div);
-  flushComputedStyle(div);
-
-  div.style.marginLeft = '100px';
-  flushComputedStyle(div);
-
-  transition = div.getAnimations()[0];
-
-  return [transition, watcher, handler];
-}
-
-// On the next frame (i.e. when events are queued), whether or not the
-// transition is still pending depends on the implementation.
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  return watcher.wait_for('transitionrun').then(function(evt) {
-    assert_equals(evt.elapsedTime, 0.0);
-  });
-}, 'Idle -> Pending or Before');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Force the transition to leave the idle phase
-  transition.startTime = document.timeline.currentTime;
-  return watcher.wait_for('transitionrun').then(function(evt) {
-    assert_equals(evt.elapsedTime, 0.0);
-  });
-}, 'Idle -> Before');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Seek to Active phase.
-  transition.currentTime = 100 * MS_PER_SEC;
-  transition.pause();
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart' ]).then(function(evt) {
-    assert_equals(handler.transitionrun, 0.0);
-    assert_equals(handler.transitionstart, 0.0);
-  });
-}, 'Idle or Pending -> Active');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Seek to After phase.
-  transition.finish();
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart',
-                            'transitionend' ]).then(function(evt) {
-    assert_equals(handler.transitionrun, 0.0);
-    assert_equals(handler.transitionstart, 0.0);
-    assert_equals(handler.transitionend, 100.0);
-  });
-}, 'Idle or Pending -> After');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-
-  return Promise.all([ watcher.wait_for('transitionrun'),
-                       transition.ready ]).then(function() {
-    transition.currentTime = 100 * MS_PER_SEC;
-    return watcher.wait_for('transitionstart');
-  }).then(function() {
-    assert_equals(handler.transitionstart, 0.0);
-  });
-}, 'Before -> Active');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  return Promise.all([ watcher.wait_for('transitionrun'),
-                       transition.ready ]).then(function() {
-    // Seek to After phase.
-    transition.currentTime = 200 * MS_PER_SEC;
-    return watcher.wait_for([ 'transitionstart', 'transitionend' ]);
-  }).then(function(evt) {
-    assert_equals(handler.transitionstart, 0.0);
-    assert_equals(handler.transitionend, 100.0);
-  });
-}, 'Before -> After');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Seek to Active phase.
-  transition.currentTime = 100 * MS_PER_SEC;
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart' ]).then(function(evt) {
-    // Seek to Before phase.
-    transition.currentTime = 0;
-    return watcher.wait_for('transitionend');
-  }).then(function(evt) {
-    assert_equals(evt.elapsedTime, 0.0);
-  });
-}, 'Active -> Before');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Seek to Active phase.
-  transition.currentTime = 100 * MS_PER_SEC;
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart' ]).then(function(evt) {
-    // Seek to After phase.
-    transition.currentTime = 200 * MS_PER_SEC;
-    return watcher.wait_for('transitionend');
-  }).then(function(evt) {
-    assert_equals(evt.elapsedTime, 100.0);
-  });
-}, 'Active -> After');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Seek to After phase.
-  transition.finish();
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart',
-                            'transitionend' ]).then(function(evt) {
-    // Seek to Before phase.
-    transition.currentTime = 0;
-    return watcher.wait_for([ 'transitionstart', 'transitionend' ]);
-  }).then(function(evt) {
-    assert_equals(handler.transitionstart, 100.0);
-    assert_equals(handler.transitionend, 0.0);
-  });
-}, 'After -> Before');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-  // Seek to After phase.
-  transition.finish();
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart',
-                            'transitionend' ]).then(function(evt) {
-    // Seek to Active phase.
-    transition.currentTime = 100 * MS_PER_SEC;
-    return watcher.wait_for('transitionstart');
-  }).then(function(evt) {
-    assert_equals(evt.elapsedTime, 100.0);
-  });
-}, 'After -> Active');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] =
-    setupTransition(t, 'transition: margin-left 100s -50s');
-
-  return watcher.wait_for([ 'transitionrun',
-                            'transitionstart' ]).then(function() {
-    assert_equals(handler.transitionrun, 50.0);
-    assert_equals(handler.transitionstart, 50.0);
-    transition.finish();
-    return watcher.wait_for('transitionend');
-  }).then(function(evt) {
-    assert_equals(evt.elapsedTime, 100.0);
-  });
-}, 'Calculating the interval start and end time with negative start delay.');
-
-promise_test(function(t) {
-  var [transition, watcher, handler] = setupTransition(t);
-
-  return watcher.wait_for('transitionrun').then(function(evt) {
-    // We can't set the end delay via generated effect timing.
-    // Because CSS-Transition use the AnimationEffectTimingReadOnly.
-    transition.effect = new KeyframeEffect(handler.target,
-                                           { marginleft: [ '0px', '100px' ]},
-                                           { duration: 100 * MS_PER_SEC,
-                                             endDelay: -50 * MS_PER_SEC });
-    // Seek to Before and play.
-    transition.cancel();
-    transition.play();
-    return watcher.wait_for('transitionstart');
-  }).then(function() {
-    assert_equals(handler.transitionstart, 0.0);
-
-    // Seek to After phase.
-    transition.finish();
-    return watcher.wait_for('transitionend');
-  }).then(function(evt) {
-    assert_equals(evt.elapsedTime, 50.0);
-  });
-}, 'Calculating the interval start and end time with negative end delay.');
-
-done();
-</script>
-</body>
-</html>
diff --git a/dom/animation/test/css-transitions/file_event-dispatch.html b/dom/animation/test/css-transitions/file_event-dispatch.html
new file mode 100644
index 000000000..7140cda36
--- /dev/null
+++ b/dom/animation/test/css-transitions/file_event-dispatch.html
@@ -0,0 +1,474 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>Tests for CSS-Transition events</title>
+<link rel="help" href="https://drafts.csswg.org/css-transitions-2/#transition-events">
+<script src="../testcommon.js"></script>
+<body>
+<script>
+'use strict';
+
+/**
+ * Helper class to record the elapsedTime member of each event.
+ * The EventWatcher class in testharness.js allows us to wait on
+ * multiple events in a certain order but only records the event
+ * parameters of the most recent event.
+ */
+function TransitionEventHandler(target) {
+  this.target = target;
+  this.target.ontransitionrun = function(evt) {
+    this.transitionrun = evt.elapsedTime;
+  }.bind(this);
+  this.target.ontransitionstart = function(evt) {
+    this.transitionstart = evt.elapsedTime;
+  }.bind(this);
+  this.target.ontransitionend = function(evt) {
+    this.transitionend = evt.elapsedTime;
+  }.bind(this);
+  this.target.ontransitioncancel = function(evt) {
+    this.transitioncancel = evt.elapsedTime;
+  }.bind(this);
+}
+
+TransitionEventHandler.prototype.clear = function() {
+  this.transitionrun    = undefined;
+  this.transitionstart  = undefined;
+  this.transitionend    = undefined;
+  this.transitioncancel = undefined;
+};
+
+function setupTransition(t, transitionStyle) {
+  var div = addDiv(t, { style: 'transition: ' + transitionStyle });
+  var watcher = new EventWatcher(t, div, [ 'transitionrun',
+                                           'transitionstart',
+                                           'transitionend',
+                                           'transitioncancel' ]);
+  flushComputedStyle(div);
+
+  div.style.marginLeft = '100px';
+  var transition = div.getAnimations()[0];
+
+  return [transition, watcher, div];
+}
+
+// On the next frame (i.e. when events are queued), whether or not the
+// transition is still pending depends on the implementation.
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+  return watcher.wait_for('transitionrun').then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Idle -> Pending or Before');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+  // Force the transition to leave the idle phase
+  transition.startTime = document.timeline.currentTime;
+  return watcher.wait_for('transitionrun').then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Idle -> Before');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+  var handler = new TransitionEventHandler(div);
+
+  // Seek to Active phase.
+  transition.currentTime = 100 * MS_PER_SEC;
+  transition.pause();
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    assert_equals(handler.transitionrun, 0.0);
+    assert_equals(handler.transitionstart, 0.0);
+  });
+}, 'Idle or Pending -> Active');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+  var handler = new TransitionEventHandler(div);
+
+  // Seek to After phase.
+  transition.finish();
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart',
+                            'transitionend' ]).then(function(evt) {
+    assert_equals(handler.transitionrun, 0.0);
+    assert_equals(handler.transitionstart, 0.0);
+    assert_equals(handler.transitionend, 100.0);
+  });
+}, 'Idle or Pending -> After');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  return Promise.all([ watcher.wait_for('transitionrun'),
+                       transition.ready ]).then(function() {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Before -> Idle (display: none)');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  return Promise.all([ watcher.wait_for('transitionrun'),
+                       transition.ready ]).then(function() {
+    // Make idle
+    transition.timeline = null;
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Before -> Idle (Animation.timeline = null)');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  return Promise.all([ watcher.wait_for('transitionrun'),
+                       transition.ready ]).then(function() {
+    transition.currentTime = 100 * MS_PER_SEC;
+    return watcher.wait_for('transitionstart');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Before -> Active');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+  var handler = new TransitionEventHandler(div);
+
+  return Promise.all([ watcher.wait_for('transitionrun'),
+                       transition.ready ]).then(function() {
+    // Seek to After phase.
+    transition.currentTime = 200 * MS_PER_SEC;
+    return watcher.wait_for([ 'transitionstart', 'transitionend' ]);
+  }).then(function(evt) {
+    assert_equals(handler.transitionstart, 0.0);
+    assert_equals(handler.transitionend, 100.0);
+  });
+}, 'Before -> After');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s');
+
+  // Seek to Active start position.
+  transition.pause();
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Active -> Idle, no delay (display: none)');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s');
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    transition.currentTime = 0;
+    transition.timeline = null;
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Active -> Idle, no delay (Animation.timeline = null)');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+  // Pause so the currentTime is fixed and we can accurately compare the event
+  // time in transition cancel events.
+  transition.pause();
+
+  // Seek to Active phase.
+  transition.currentTime = 100 * MS_PER_SEC;
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Active -> Idle, with positive delay (display: none)');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  // Seek to Active phase.
+  transition.currentTime = 100 * MS_PER_SEC;
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    transition.currentTime = 100 * MS_PER_SEC;
+    transition.timeline = null;
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Active -> Idle, with positive delay (Animation.timeline = null)');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s -50s');
+
+  // Pause so the currentTime is fixed and we can accurately compare the event
+  // time in transition cancel events.
+  transition.pause();
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 50.0);
+  });
+}, 'Active -> Idle, with negative delay (display: none)');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s -50s');
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    transition.currentTime = 50 * MS_PER_SEC;
+    transition.timeline = null;
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Active -> Idle, with negative delay (Animation.timeline = null)');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+  // Seek to Active phase.
+  transition.currentTime = 100 * MS_PER_SEC;
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Seek to Before phase.
+    transition.currentTime = 0;
+    return watcher.wait_for('transitionend');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 0.0);
+  });
+}, 'Active -> Before');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+  // Seek to Active phase.
+  transition.currentTime = 100 * MS_PER_SEC;
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Seek to After phase.
+    transition.currentTime = 200 * MS_PER_SEC;
+    return watcher.wait_for('transitionend');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 100.0);
+  });
+}, 'Active -> After');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+  var handler = new TransitionEventHandler(div);
+
+  // Seek to After phase.
+  transition.finish();
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart',
+                            'transitionend' ]).then(function(evt) {
+    // Seek to Before phase.
+    transition.currentTime = 0;
+    return watcher.wait_for([ 'transitionstart', 'transitionend' ]);
+  }).then(function(evt) {
+    assert_equals(handler.transitionstart, 100.0);
+    assert_equals(handler.transitionend, 0.0);
+  });
+}, 'After -> Before');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s 100s');
+  // Seek to After phase.
+  transition.finish();
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart',
+                            'transitionend' ]).then(function(evt) {
+    // Seek to Active phase.
+    transition.currentTime = 100 * MS_PER_SEC;
+    return watcher.wait_for('transitionstart');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 100.0);
+  });
+}, 'After -> Active');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s -50s');
+  var handler = new TransitionEventHandler(div);
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function() {
+    assert_equals(handler.transitionrun, 50.0);
+    assert_equals(handler.transitionstart, 50.0);
+    transition.finish();
+    return watcher.wait_for('transitionend');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 100.0);
+  });
+}, 'Calculating the interval start and end time with negative start delay.');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+  var handler = new TransitionEventHandler(div);
+
+  return watcher.wait_for('transitionrun').then(function(evt) {
+    // We can't set the end delay via generated effect timing.
+    // Because CSS-Transition use the AnimationEffectTimingReadOnly.
+    transition.effect = new KeyframeEffect(div,
+                                           { marginleft: [ '0px', '100px' ]},
+                                           { duration: 100 * MS_PER_SEC,
+                                             endDelay: -50 * MS_PER_SEC });
+    // Seek to Before and play.
+    transition.cancel();
+    transition.play();
+    return watcher.wait_for([ 'transitioncancel',
+                              'transitionrun',
+                              'transitionstart' ]);
+  }).then(function() {
+    assert_equals(handler.transitionstart, 0.0);
+
+    // Seek to After phase.
+    transition.finish();
+    return watcher.wait_for('transitionend');
+  }).then(function(evt) {
+    assert_equals(evt.elapsedTime, 50.0);
+  });
+}, 'Calculating the interval start and end time with negative end delay.');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  return watcher.wait_for('transitionrun').then(function() {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    return watcher.wait_for('transitioncancel');
+  }).then(function() {
+    transition.cancel();
+    // Then wait a couple of frames and check that no event was dispatched
+    return waitForAnimationFrames(2);
+  });
+}, 'Call Animation.cancel after cancelling transition.');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  return watcher.wait_for('transitionrun').then(function(evt) {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    transition.play();
+    watcher.wait_for([ 'transitioncancel',
+                       'transitionrun',
+                       'transitionstart' ]);
+  });
+}, 'Restart transition after cancelling transition immediately');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s 100s');
+
+  return watcher.wait_for('transitionrun').then(function(evt) {
+    // Make idle
+    div.style.display = 'none';
+    flushComputedStyle(div);
+    transition.play();
+    transition.cancel();
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    // Then wait a couple of frames and check that no event was dispatched
+    return waitForAnimationFrames(2);
+  });
+}, 'Call Animation.cancel after restarting transition immediately');
+
+promise_test(function(t) {
+  var [transition, watcher] =
+    setupTransition(t, 'margin-left 100s');
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    // Make idle
+    transition.timeline = null;
+    return watcher.wait_for('transitioncancel');
+  }).then(function(evt) {
+    transition.timeline = document.timeline;
+    transition.play();
+
+    return watcher.wait_for(['transitionrun', 'transitionstart']);
+  });
+}, 'Set timeline and play transition after clear the timeline');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s');
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function() {
+    transition.cancel();
+    return watcher.wait_for('transitioncancel');
+  }).then(function() {
+    // Make After phase
+    transition.effect = null;
+
+    // Then wait a couple of frames and check that no event was dispatched
+    return waitForAnimationFrames(2);
+  });
+}, 'Set null target effect after cancel the transition');
+
+promise_test(function(t) {
+  var [transition, watcher, div] =
+    setupTransition(t, 'margin-left 100s');
+
+  return watcher.wait_for([ 'transitionrun',
+                            'transitionstart' ]).then(function(evt) {
+    transition.effect = null;
+    return watcher.wait_for('transitionend');
+  }).then(function(evt) {
+    transition.cancel();
+    return watcher.wait_for('transitioncancel');
+  });
+}, 'Cancel the transition after clearing the target effect');
+
+done();
+</script>
+</body>
+</html>
diff --git a/dom/animation/test/css-transitions/file_setting-effect.html b/dom/animation/test/css-transitions/file_setting-effect.html
index c61877194..81279ea55 100644
--- a/dom/animation/test/css-transitions/file_setting-effect.html
+++ b/dom/animation/test/css-transitions/file_setting-effect.html
@@ -7,6 +7,8 @@
 
 promise_test(function(t) {
   var div = addDiv(t);
+  var watcher = new EventWatcher(t, div, [ 'transitionend',
+                                           'transitioncancel' ]);
   div.style.left = '0px';
 
   div.style.transition = 'left 100s';
@@ -20,11 +22,14 @@ promise_test(function(t) {
     assert_equals(transition.transitionProperty, 'left');
     assert_equals(transition.playState, 'finished');
     assert_equals(window.getComputedStyle(div).left, '100px');
+    return watcher.wait_for('transitionend');
   });
 }, 'Test for removing a transition effect');
 
 promise_test(function(t) {
   var div = addDiv(t);
+  var watcher = new EventWatcher(t, div, [ 'transitionend',
+                                           'transitioncancel' ]);
   div.style.left = '0px';
 
   div.style.transition = 'left 100s';
@@ -46,6 +51,8 @@ promise_test(function(t) {
 
 promise_test(function(t) {
   var div = addDiv(t);
+  var watcher = new EventWatcher(t, div, [ 'transitionend',
+                                           'transitioncancel' ]);
   div.style.left = '0px';
   div.style.width = '0px';
 
@@ -65,6 +72,8 @@ promise_test(function(t) {
 
 promise_test(function(t) {
   var div = addDiv(t);
+  var watcher = new EventWatcher(t, div, [ 'transitionend',
+                                           'transitioncancel' ]);
   div.style.left = '0px';
   div.style.width = '0px';
 
diff --git a/dom/animation/test/css-transitions/test_csstransition-events.html b/dom/animation/test/css-transitions/test_event-dispatch.html
index 92559ad67..c90431cd1 100644
--- a/dom/animation/test/css-transitions/test_csstransition-events.html
+++ b/dom/animation/test/css-transitions/test_event-dispatch.html
@@ -9,6 +9,6 @@ setup({explicit_done: true});
 SpecialPowers.pushPrefEnv(
   { "set": [["dom.animations-api.core.enabled", true]]},
   function() {
-    window.open("file_csstransition-events.html");
+    window.open("file_event-dispatch.html");
   });
 </script>
diff --git a/dom/animation/test/mochitest.ini b/dom/animation/test/mochitest.ini
index 07e04d4d6..db6dffada 100644
--- a/dom/animation/test/mochitest.ini
+++ b/dom/animation/test/mochitest.ini
@@ -30,11 +30,11 @@ support-files =
   css-transitions/file_animation-pausing.html
   css-transitions/file_animation-ready.html
   css-transitions/file_animation-starttime.html
-  css-transitions/file_csstransition-events.html
   css-transitions/file_csstransition-transitionproperty.html
   css-transitions/file_document-get-animations.html
   css-transitions/file_effect-target.html
   css-transitions/file_element-get-animations.html
+  css-transitions/file_event-dispatch.html
   css-transitions/file_keyframeeffect-getkeyframes.html
   css-transitions/file_pseudoElement-get-animations.html
   css-transitions/file_setting-effect.html
@@ -86,11 +86,11 @@ support-files =
 [css-transitions/test_animation-pausing.html]
 [css-transitions/test_animation-ready.html]
 [css-transitions/test_animation-starttime.html]
-[css-transitions/test_csstransition-events.html]
 [css-transitions/test_csstransition-transitionproperty.html]
 [css-transitions/test_document-get-animations.html]
 [css-transitions/test_effect-target.html]
 [css-transitions/test_element-get-animations.html]
+[css-transitions/test_event-dispatch.html]
 [css-transitions/test_keyframeeffect-getkeyframes.html]
 [css-transitions/test_pseudoElement-get-animations.html]
 [css-transitions/test_setting-effect.html]
diff --git a/layout/style/test/test_animations_event_handler_attribute.html b/layout/style/test/test_animations_event_handler_attribute.html
index 23a749daa..036a77779 100644
--- a/layout/style/test/test_animations_event_handler_attribute.html
+++ b/layout/style/test/test_animations_event_handler_attribute.html
@@ -88,11 +88,12 @@ checkReceivedEvents("animationend", targets);
 
 targets.forEach(div => { div.remove(); });
 
-// 2. Test CSS Transition event handlers.
+// 2a. Test CSS Transition event handlers (without transitioncancel)
 
 var targets = createAndRegisterTargets([ 'ontransitionrun',
                                          'ontransitionstart',
-                                         'ontransitionend' ]);
+                                         'ontransitionend',
+                                         'ontransitioncancel' ]);
 targets.forEach(div => {
   div.style.transition = 'margin-left 100ms 200ms';
   getComputedStyle(div).marginLeft; // flush
@@ -111,6 +112,31 @@ checkReceivedEvents("transitionend", targets);
 
 targets.forEach(div => { div.remove(); });
 
+// 2b. Test CSS Transition cancel event handler.
+
+var targets = createAndRegisterTargets([ 'ontransitioncancel' ]);
+targets.forEach(div => {
+  div.style.transition = 'margin-left 100ms 200ms';
+  getComputedStyle(div).marginLeft; // flush
+  div.style.marginLeft = "200px";
+  getComputedStyle(div).marginLeft; // flush
+});
+
+advance_clock(200);
+
+targets.forEach(div => {
+  div.style.display = "none"
+});
+getComputedStyle(targets[0]).display; // flush
+
+advance_clock(0);
+checkReceivedEvents("transitioncancel", targets);
+
+advance_clock(100);
+targets.forEach( div => { is(div.receivedEventType, undefined); });
+
+targets.forEach(div => { div.remove(); });
+
 // 3. Test prefixed CSS Animation event handlers.
 
 var targets = createAndRegisterTargets([ 'onwebkitanimationstart',
diff --git a/layout/style/test/test_animations_event_order.html b/layout/style/test/test_animations_event_order.html
index f948bf0a5..7204934d2 100644
--- a/layout/style/test/test_animations_event_order.html
+++ b/layout/style/test/test_animations_event_order.html
@@ -48,7 +48,8 @@ var gDisplay = document.getElementById('display');
   'animationend',
   'transitionrun',
   'transitionstart',
-  'transitionend' ]
+  'transitionend',
+  'transitioncancel' ]
   .forEach(event =>
              gDisplay.addEventListener(event,
                                        event => gEventsReceived.push(event),
@@ -623,6 +624,43 @@ checkEventOrder([ divs[0], 'transitionrun' ],
 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);
+});
+
+divs[0].style.transition = 'margin-left 10s 5s';
+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;
+advance_clock(10 * 1000);
+
+checkEventOrder([ divs[0], 'transitionrun' ],
+                [ divs[1], 'transitionrun' ],
+                [ divs[1], 'transitionstart' ],
+                [ divs[0], 'transitionstart' ],
+                [ divs[1], 'transitioncancel' ],
+                [ divs[0], 'transitioncancel' ],
+                'Simultaneous transitionrun/start/cancel on siblings');
+
+divs.forEach(div => div.remove());
+divs = [];
+
 SpecialPowers.DOMWindowUtils.restoreNormalRefresh();
 
 </script>