Emit TransitionEnd events in the layout thread and process it in the script thread

21 files changed, 103 insertions, 62 deletions

diff --git a/components/layout/animation.rs b/components/layout/animation.rs
index 71a388dcf0c..22387dff562 100644
--- a/components/layout/animation.rs
+++ b/components/layout/animation.rs
@@ -10,7 +10,7 @@ use gfx::display_list::OpaqueNode;
 use ipc_channel::ipc::IpcSender;
 use msg::constellation_msg::PipelineId;
 use script_layout_interface::restyle_damage::RestyleDamage;
-use script_traits::{AnimationState, LayoutMsg as ConstellationMsg};
+use script_traits::{AnimationState, ConstellationControlMsg, LayoutMsg as ConstellationMsg};
 use std::collections::HashMap;
 use std::sync::mpsc::Receiver;
 use style::animation::{Animation, update_style_for_animation};
@@ -21,6 +21,7 @@ use style::timer::Timer;
 /// Also expire any old animations that have completed, inserting them into
 /// `expired_animations`.
 pub fn update_animation_state(constellation_chan: &IpcSender<ConstellationMsg>,
+                              script_chan: &IpcSender<ConstellationControlMsg>,
                               running_animations: &mut HashMap<OpaqueNode, Vec<Animation>>,
                               expired_animations: &mut HashMap<OpaqueNode, Vec<Animation>>,
                               new_animations_receiver: &Receiver<Animation>,
@@ -70,7 +71,7 @@ pub fn update_animation_state(constellation_chan: &IpcSender<ConstellationMsg>,
         let mut animations_still_running = vec![];
         for mut running_animation in running_animations.drain(..) {
             let still_running = !running_animation.is_expired() && match running_animation {
-                Animation::Transition(_, started_at, ref frame, _expired) => {
+                Animation::Transition(_, _, started_at, ref frame, _expired) => {
                     now < started_at + frame.duration
                 }
                 Animation::Keyframes(_, _, ref mut state) => {
@@ -85,6 +86,13 @@ pub fn update_animation_state(constellation_chan: &IpcSender<ConstellationMsg>,
                 continue
             }
 
+            if let Animation::Transition(_, unsafe_node, _, ref frame, _) = running_animation {
+                script_chan.send(ConstellationControlMsg::TransitionEnd(unsafe_node,
+                                                                        frame.property_animation.property_name(),
+                                                                        frame.duration))
+                           .unwrap();
+            }
+
             expired_animations.entry(*key)
                               .or_insert_with(Vec::new)
                               .push(running_animation);
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 4797b8814aa..026e9796883 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -1477,6 +1477,7 @@ impl LayoutThread {
         if let Some(mut root_flow) = self.root_flow.clone() {
             // Kick off animations if any were triggered, expire completed ones.
             animation::update_animation_state(&self.constellation_chan,
+                                              &self.script_chan,
                                               &mut *self.running_animations.write().unwrap(),
                                               &mut *self.expired_animations.write().unwrap(),
                                               &self.new_animations_receiver,
diff --git a/components/script/dom/bindings/js.rs b/components/script/dom/bindings/js.rs
index 1fd127b3b28..fc881fee3b7 100644
--- a/components/script/dom/bindings/js.rs
+++ b/components/script/dom/bindings/js.rs
@@ -444,6 +444,14 @@ impl<T: Reflectable> LayoutJS<T> {
         debug_assert!(thread_state::get().is_layout());
         *self.ptr
     }
+
+    /// Returns a reference to the interior of this JS object. This method is
+    /// safe to call because it originates from the layout thread, and it cannot
+    /// mutate DOM nodes.
+    pub fn get_for_script(&self) -> &T {
+        debug_assert!(thread_state::get().is_script());
+        unsafe { &**self.ptr }
+    }
 }
 
 /// Get an `&T` out of a `Rc<T>`
diff --git a/components/script/dom/macros.rs b/components/script/dom/macros.rs
index e69255b6aed..5935f02cde2 100644
--- a/components/script/dom/macros.rs
+++ b/components/script/dom/macros.rs
@@ -472,6 +472,7 @@ macro_rules! global_event_handlers(
         event_handler!(suspend, GetOnsuspend, SetOnsuspend);
         event_handler!(timeupdate, GetOntimeupdate, SetOntimeupdate);
         event_handler!(toggle, GetOntoggle, SetOntoggle);
+        event_handler!(transitionend, GetOntransitionend, SetOntransitionend);
         event_handler!(volumechange, GetOnvolumechange, SetOnvolumechange);
         event_handler!(waiting, GetOnwaiting, SetOnwaiting);
     )
diff --git a/components/script/dom/webidls/EventHandler.webidl b/components/script/dom/webidls/EventHandler.webidl
index 1af56394c35..1ffa128e128 100644
--- a/components/script/dom/webidls/EventHandler.webidl
+++ b/components/script/dom/webidls/EventHandler.webidl
@@ -89,6 +89,11 @@ interface GlobalEventHandlers {
            attribute EventHandler onwaiting;
 };
 
+// https://drafts.csswg.org/css-transitions/#interface-globaleventhandlers-idl
+partial interface GlobalEventHandlers {
+           attribute EventHandler ontransitionend;
+};
+
 // https://html.spec.whatwg.org/multipage/#windoweventhandlers
 [NoInterfaceObject, Exposed=(Window,Worker)]
 interface WindowEventHandlers {
diff --git a/components/script/dom/webidls/TransitionEvent.webidl b/components/script/dom/webidls/TransitionEvent.webidl
index f1e284ac02d..5e7a3ff6913 100644
--- a/components/script/dom/webidls/TransitionEvent.webidl
+++ b/components/script/dom/webidls/TransitionEvent.webidl
@@ -6,7 +6,8 @@
  * https://dom.spec.whatwg.org/#event
  */
 
-[Constructor(DOMString type, optional TransitionEventInit transitionEventInitDict)]
+[Constructor(DOMString type, optional TransitionEventInit transitionEventInitDict),
+ Exposed=Window]
 interface TransitionEvent : Event {
   readonly attribute DOMString          propertyName;
   readonly attribute float              elapsedTime;
diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index f2947bedc93..451cfe82623 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -413,7 +413,7 @@ impl<'ln> ServoLayoutNode<'ln> {
 
     /// Returns the interior of this node as a `LayoutJS`. This is highly unsafe for layout to
     /// call and as such is marked `unsafe`.
-    unsafe fn get_jsmanaged(&self) -> &LayoutJS<Node> {
+    pub unsafe fn get_jsmanaged(&self) -> &LayoutJS<Node> {
         &self.node
     }
 }
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 87d4d148253..5667bca4be5 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -23,13 +23,17 @@ use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
 use devtools_traits::CSSError;
 use document_loader::DocumentLoader;
 use dom::bindings::cell::DOMRefCell;
+use dom::bindings::codegen::Bindings::CSSStyleDeclarationBinding::CSSStyleDeclarationMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
+use dom::bindings::codegen::Bindings::EventBinding::EventInit;
 use dom::bindings::codegen::Bindings::LocationBinding::LocationMethods;
+use dom::bindings::codegen::Bindings::TransitionEventBinding::TransitionEventInit;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::conversions::{ConversionResult, FromJSValConvertible, StringificationBehavior};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root, RootCollection};
 use dom::bindings::js::{RootCollectionPtr, RootedReference};
+use dom::bindings::num::Finite;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::Reflectable;
 use dom::bindings::str::DOMString;
@@ -47,6 +51,7 @@ use dom::serviceworkerregistration::ServiceWorkerRegistration;
 use dom::servoparser::{ParserContext, ServoParser};
 use dom::servoparser::html::{ParseContext, parse_html};
 use dom::servoparser::xml::{self, parse_xml};
+use dom::transitionevent::TransitionEvent;
 use dom::uievent::UIEvent;
 use dom::window::{ReflowReason, Window};
 use dom::worker::TrustedWorkerAddress;
@@ -65,6 +70,7 @@ use js::jsapi::{JSAutoCompartment, JSContext, JS_SetWrapObjectCallbacks};
 use js::jsapi::{JSTracer, SetWindowProxyClass};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
+use layout_wrapper::ServoLayoutNode;
 use mem::heap_size_of_self_and_children;
 use msg::constellation_msg::{FrameType, LoadData, PipelineId, PipelineNamespace};
 use msg::constellation_msg::{ReferrerPolicy, WindowSizeType};
@@ -97,6 +103,7 @@ use std::sync::{Arc, Mutex};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::mpsc::{Receiver, Select, Sender, channel};
 use style::context::ReflowGoal;
+use style::dom::{TNode, UnsafeNode};
 use style::thread_state;
 use task_source::TaskSource;
 use task_source::dom_manipulation::{DOMManipulationTask, DOMManipulationTaskSource};
@@ -917,6 +924,8 @@ impl ScriptThread {
                 self.handle_webdriver_msg(pipeline_id, msg),
             ConstellationControlMsg::TickAllAnimations(pipeline_id) =>
                 self.handle_tick_all_animations(pipeline_id),
+            ConstellationControlMsg::TransitionEnd(unsafe_node, name, duration) =>
+                self.handle_transition_event(unsafe_node, name, duration),
             ConstellationControlMsg::WebFontLoaded(pipeline_id) =>
                 self.handle_web_font_loaded(pipeline_id),
             ConstellationControlMsg::DispatchFrameLoadEvent {
@@ -1523,6 +1532,35 @@ impl ScriptThread {
         document.run_the_animation_frame_callbacks();
     }
 
+    /// Handles firing of transition events.
+    #[allow(unsafe_code)]
+    fn handle_transition_event(&self, unsafe_node: UnsafeNode, name: String, duration: f64) {
+        let node = unsafe { ServoLayoutNode::from_unsafe(&unsafe_node) };
+        let node = unsafe { node.get_jsmanaged().get_for_script() };
+        let window = window_from_node(node);
+
+        if let Some(el) = node.downcast::<Element>() {
+            if &*window.GetComputedStyle(el, None).Display() == "none" {
+                return;
+            }
+        }
+
+        let init = TransitionEventInit {
+            parent: EventInit {
+                bubbles: true,
+                cancelable: false,
+            },
+            propertyName: DOMString::from(name),
+            elapsedTime: Finite::new(duration as f32).unwrap(),
+            // FIXME: Handle pseudo-elements properly
+            pseudoElement: DOMString::new()
+        };
+        let transition_event = TransitionEvent::new(window.upcast(),
+                                                    atom!("transitionend"),
+                                                    &init);
+        transition_event.upcast::<Event>().fire(node.upcast());
+    }
+
     /// Handles a Web font being loaded. Does nothing if the page no longer exists.
     fn handle_web_font_loaded(&self, pipeline_id: PipelineId) {
         if let Some(context) = self.find_child_context(pipeline_id)  {
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index 2220a9cf2e1..c5fa8fee4e6 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -66,7 +66,7 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use std::collections::HashMap;
 use std::fmt;
 use std::sync::mpsc::{Receiver, Sender};
-use style_traits::{PagePx, ViewportPx};
+use style_traits::{PagePx, UnsafeNode, ViewportPx};
 use url::Url;
 use util::ipc::OptionalOpaqueIpcSender;
 use webdriver_msg::{LoadStatus, WebDriverScriptCommand};
@@ -197,6 +197,8 @@ pub enum ConstellationControlMsg {
     WebDriverScriptCommand(PipelineId, WebDriverScriptCommand),
     /// Notifies script thread that all animations are done
     TickAllAnimations(PipelineId),
+    /// Notifies the script thread of a transition end
+    TransitionEnd(UnsafeNode, String, f64),
     /// Notifies the script thread that a new Web font has been loaded, and thus the page should be
     /// reflowed.
     WebFontLoaded(PipelineId),
@@ -238,6 +240,7 @@ impl fmt::Debug for ConstellationControlMsg {
             FocusIFrame(..) => "FocusIFrame",
             WebDriverScriptCommand(..) => "WebDriverScriptCommand",
             TickAllAnimations(..) => "TickAllAnimations",
+            TransitionEnd(..) => "TransitionEnd",
             WebFontLoaded(..) => "WebFontLoaded",
             DispatchFrameLoadEvent { .. } => "DispatchFrameLoadEvent",
             FramedContentChanged(..) => "FramedContentChanged",
diff --git a/components/style/animation.rs b/components/style/animation.rs
index 9e55ca2e52a..bf74fa643f2 100644
--- a/components/style/animation.rs
+++ b/components/style/animation.rs
@@ -6,7 +6,7 @@
 
 use bezier::Bezier;
 use context::SharedStyleContext;
-use dom::OpaqueNode;
+use dom::{OpaqueNode, UnsafeNode};
 use euclid::point::Point2D;
 use keyframes::{KeyframesStep, KeyframesStepValue};
 use properties::{self, ComputedValues, Importance};
@@ -186,7 +186,7 @@ pub enum Animation {
     /// the f64 field is the start time as returned by `time::precise_time_s()`.
     ///
     /// The `bool` field is werther this animation should no longer run.
-    Transition(OpaqueNode, f64, AnimationFrame, bool),
+    Transition(OpaqueNode, UnsafeNode, f64, AnimationFrame, bool),
     /// A keyframes animation is identified by a name, and can have a
     /// node-dependent state (i.e. iteration count, etc.).
     Keyframes(OpaqueNode, Atom, KeyframesAnimationState),
@@ -197,7 +197,7 @@ impl Animation {
     pub fn mark_as_expired(&mut self) {
         debug_assert!(!self.is_expired());
         match *self {
-            Animation::Transition(_, _, _, ref mut expired) => *expired = true,
+            Animation::Transition(_, _, _, _, ref mut expired) => *expired = true,
             Animation::Keyframes(_, _, ref mut state) => state.expired = true,
         }
     }
@@ -205,7 +205,7 @@ impl Animation {
     #[inline]
     pub fn is_expired(&self) -> bool {
         match *self {
-            Animation::Transition(_, _, _, expired) => expired,
+            Animation::Transition(_, _, _, _, expired) => expired,
             Animation::Keyframes(_, _, ref state) => state.expired,
         }
     }
@@ -213,7 +213,7 @@ impl Animation {
     #[inline]
     pub fn node(&self) -> &OpaqueNode {
         match *self {
-            Animation::Transition(ref node, _, _, _) => node,
+            Animation::Transition(ref node, _, _, _, _) => node,
             Animation::Keyframes(ref node, _, _) => node,
         }
     }
@@ -246,6 +246,10 @@ pub struct PropertyAnimation {
 }
 
 impl PropertyAnimation {
+    pub fn property_name(&self) -> String {
+        self.property.name()
+    }
+
     /// Creates a new property animation for the given transition index and old and new styles.
     /// Any number of animations may be returned, from zero (if the property did not animate) to
     /// one (for a single transition property) to arbitrarily many (for `all`).
@@ -341,7 +345,8 @@ impl PropertyAnimation {
 // TODO(emilio): Take rid of this mutex splitting SharedLayoutContex into a
 // cloneable part and a non-cloneable part..
 pub fn start_transitions_if_applicable(new_animations_sender: &Sender<Animation>,
-                                       node: OpaqueNode,
+                                       opaque_node: OpaqueNode,
+                                       unsafe_node: UnsafeNode,
                                        old_style: &ComputedValues,
                                        new_style: &mut Arc<ComputedValues>,
                                        timer: &Timer)
@@ -362,7 +367,7 @@ pub fn start_transitions_if_applicable(new_animations_sender: &Sender<Animation>
             let start_time =
                 now + (box_style.transition_delay_mod(i).seconds() as f64);
             new_animations_sender
-                .send(Animation::Transition(node, start_time, AnimationFrame {
+                .send(Animation::Transition(opaque_node, unsafe_node, start_time, AnimationFrame {
                     duration: box_style.transition_duration_mod(i).seconds() as f64,
                     property_animation: property_animation,
                 }, /* is_expired = */ false)).unwrap();
@@ -499,7 +504,7 @@ pub fn update_style_for_animation(context: &SharedStyleContext,
     debug_assert!(!animation.is_expired());
 
     match *animation {
-        Animation::Transition(_, start_time, ref frame, _) => {
+        Animation::Transition(_, _, start_time, ref frame, _) => {
             debug!("update_style_for_animation: transition found");
             let now = context.timer.seconds();
             let mut new_style = (*style).clone();
@@ -673,7 +678,7 @@ pub fn complete_expired_transitions(node: OpaqueNode, style: &mut Arc<ComputedVa
         if let Some(ref animations) = animations_to_expire {
             for animation in *animations {
                 // TODO: support animation-fill-mode
-                if let Animation::Transition(_, _, ref frame, _) = *animation {
+                if let Animation::Transition(_, _, _, ref frame, _) = *animation {
                     frame.property_animation.update(Arc::make_mut(style), 1.0);
                 }
             }
diff --git a/components/style/dom.rs b/components/style/dom.rs
index 5b2bbcb135e..3c61a5533d9 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -19,9 +19,7 @@ use std::ops::BitOr;
 use std::sync::Arc;
 use string_cache::{Atom, Namespace};
 
-/// Opaque type stored in type-unsafe work queues for parallel layout.
-/// Must be transmutable to and from TNode.
-pub type UnsafeNode = (usize, usize);
+pub use style_traits::UnsafeNode;
 
 /// An opaque handle to a node, which, unlike UnsafeNode, cannot be transformed
 /// back into a non-opaque representation. The only safe operation that can be
diff --git a/components/style/matching.rs b/components/style/matching.rs
index 18e45a32ece..35e31b66062 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -569,6 +569,7 @@ trait PrivateMatchMethods: TNode {
                     animation::start_transitions_if_applicable(
                         new_animations_sender,
                         this_opaque,
+                        self.to_unsafe(),
                         &**style,
                         &mut this_style,
                         &shared_context.timer);
diff --git a/components/style/properties/helpers/animated_properties.mako.rs b/components/style/properties/helpers/animated_properties.mako.rs
index 384e5436976..c0f2fbe3b28 100644
--- a/components/style/properties/helpers/animated_properties.mako.rs
+++ b/components/style/properties/helpers/animated_properties.mako.rs
@@ -101,6 +101,16 @@ pub enum AnimatedProperty {
 }
 
 impl AnimatedProperty {
+    pub fn name(&self) -> String {
+        match *self {
+            % for prop in data.longhands:
+                % if prop.animatable:
+                    AnimatedProperty::${prop.camel_case}(..) => "${prop.name}".to_owned(),
+                % endif
+            % endfor
+        }
+    }
+
     pub fn does_animate(&self) -> bool {
         match *self {
             % for prop in data.longhands:
diff --git a/components/style_traits/lib.rs b/components/style_traits/lib.rs
index 54657108341..449aca96ee3 100644
--- a/components/style_traits/lib.rs
+++ b/components/style_traits/lib.rs
@@ -27,6 +27,10 @@ extern crate rustc_serialize;
 #[cfg(feature = "servo")] extern crate serde;
 #[cfg(feature = "servo")] #[macro_use] extern crate serde_derive;
 
+/// Opaque type stored in type-unsafe work queues for parallel layout.
+/// Must be transmutable to and from TNode.
+pub type UnsafeNode = (usize, usize);
+
 /// One CSS "px" in the coordinate system of the "initial viewport":
 /// http://www.w3.org/TR/css-device-adapt/#initial-viewport
 ///
diff --git a/tests/wpt/metadata-css/css-transitions-1_dev/html/changing-while-transition.htm.ini b/tests/wpt/metadata-css/css-transitions-1_dev/html/changing-while-transition.htm.ini
index 3ea02d5025a..e1464721388 100644
--- a/tests/wpt/metadata-css/css-transitions-1_dev/html/changing-while-transition.htm.ini
+++ b/tests/wpt/metadata-css/css-transitions-1_dev/html/changing-while-transition.htm.ini
@@ -1,5 +1,7 @@
 [changing-while-transition.htm]
   type: testharness
+  [changing transition-property / values]
+    expected: FAIL
   [changing transition-duration / values]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-001.htm.ini b/tests/wpt/metadata-css/css-transitions-1_dev/html/events-001.htm.ini
index 7bbfe535d94..69679779896 100644
--- a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-001.htm.ini
+++ b/tests/wpt/metadata-css/css-transitions-1_dev/html/events-001.htm.ini
@@ -1,14 +1,5 @@
 [events-001.htm]
   type: testharness
-  [transition:all, changing padding-left / events]
-    expected: FAIL
-
-  [transition:all, changing padding / events]
-    expected: FAIL
-
-  [transition:all, changing padding but not padding-bottom / events]
-    expected: FAIL
-
   [transition:padding, changing padding-left / events]
     expected: FAIL
 
@@ -18,12 +9,3 @@
   [transition:padding, changing padding but not padding-bottom / events]
     expected: FAIL
 
-  [transition:padding-left, changing padding-left / events]
-    expected: FAIL
-
-  [transition:padding-left, changing padding / events]
-    expected: FAIL
-
-  [transition:padding-left, changing padding but not padding-bottom / events]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-002.htm.ini b/tests/wpt/metadata-css/css-transitions-1_dev/html/events-002.htm.ini
deleted file mode 100644
index c46bd5155b2..00000000000
--- a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-002.htm.ini
+++ /dev/null
@@ -1,8 +0,0 @@
-[events-002.htm]
-  type: testharness
-  [transitions:all, changing padding-left from nothing / events]
-    expected: FAIL
-
-  [transitions:all, changing padding from nothing / events]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-003.htm.ini b/tests/wpt/metadata-css/css-transitions-1_dev/html/events-003.htm.ini
deleted file mode 100644
index 15ac729dffd..00000000000
--- a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-003.htm.ini
+++ /dev/null
@@ -1,8 +0,0 @@
-[events-003.htm]
-  type: testharness
-  [duration: 0.1s, delay: -0.05s / events]
-    expected: FAIL
-
-  [duration: 0.1s, delay: -0.1s / events]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-004.htm.ini b/tests/wpt/metadata-css/css-transitions-1_dev/html/events-004.htm.ini
deleted file mode 100644
index 3b5af3606d9..00000000000
--- a/tests/wpt/metadata-css/css-transitions-1_dev/html/events-004.htm.ini
+++ /dev/null
@@ -1,8 +0,0 @@
-[events-004.htm]
-  type: testharness
-  [repeating lists / events]
-    expected: FAIL
-
-  [truncating lists / events]
-    expected: FAIL
-
diff --git a/tests/wpt/mozilla/meta/css/incremental_trailing_whitespace_a.html.ini b/tests/wpt/mozilla/meta/css/incremental_trailing_whitespace_a.html.ini
deleted file mode 100644
index 2a72cc1da38..00000000000
--- a/tests/wpt/mozilla/meta/css/incremental_trailing_whitespace_a.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[incremental_trailing_whitespace_a.html]
-  type: reftest
-  disabled: https://github.com/servo/servo/issues/10473
diff --git a/tests/wpt/mozilla/tests/mozilla/interfaces.html b/tests/wpt/mozilla/tests/mozilla/interfaces.html
index 8599e2a1780..8c318e4d7d3 100644
--- a/tests/wpt/mozilla/tests/mozilla/interfaces.html
+++ b/tests/wpt/mozilla/tests/mozilla/interfaces.html
@@ -161,6 +161,7 @@ test_interfaces([
   "Touch",
   "TouchEvent",
   "TouchList",
+  "TransitionEvent",
   "TreeWalker",
   "UIEvent",
   "URL",