Web Animations: Implement the AnimationPlayer finished promise

Source/core/animation/AnimationPlayer.h

Index: Source/core/animation/AnimationPlayer.h
diff --git a/Source/core/animation/AnimationPlayer.h b/Source/core/animation/AnimationPlayer.h
index 00feea30b5cbc8918747d6224d09095df48faa65..69da623aaceb381516076a5bb37a1b8148c48fdb 100644
--- a/Source/core/animation/AnimationPlayer.h
+++ b/Source/core/animation/AnimationPlayer.h
@@ -31,8 +31,11 @@
 #ifndef AnimationPlayer_h
 #define AnimationPlayer_h
 
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptPromiseProperty.h"
 #include "core/animation/AnimationNode.h"
 #include "core/dom/ActiveDOMObject.h"
+#include "core/dom/DOMException.h"
 #include "core/events/EventTarget.h"
 #include "platform/heap/Handle.h"
 #include "wtf/RefPtr.h"
@@ -89,6 +92,8 @@ public:
     void reverse();
     void finish(ExceptionState&);
 
+    ScriptPromise finished(ScriptState*);
+
     bool playing() const { return !(playStateInternal() == Idle || limited() || m_paused || m_isPausedForTesting); }
     bool limited() const { return limited(currentTimeInternal()); }
 
@@ -183,6 +188,9 @@ private:
 
     unsigned m_sequenceNumber;
 
+    typedef ScriptPromiseProperty<RawPtrWillBeMember<AnimationPlayer>, RawPtrWillBeMember<AnimationPlayer>, RefPtrWillBeMember<DOMException> > AnimationPlayerPromise;
+    PersistentWillBeMember<AnimationPlayerPromise> m_finishedPromise;
+
     RefPtrWillBeMember<AnimationNode> m_content;
     RawPtrWillBeMember<AnimationTimeline> m_timeline;
     // Reflects all pausing, including via pauseForTesting().
@@ -236,7 +244,7 @@ private:
         ~PlayStateUpdateScope();
     private:
         RawPtrWillBeMember<AnimationPlayer> m_player;
-        AnimationPlayState m_initial;
+        AnimationPlayState m_initialPlayState;
         CompositorPendingChange m_compositorPendingChange;
     };