Implement DocumentTimeline

third_party/WebKit/Source/core/animation/AnimationTimeline.h

Index: third_party/WebKit/Source/core/animation/AnimationTimeline.h
diff --git a/third_party/WebKit/Source/core/animation/AnimationTimeline.h b/third_party/WebKit/Source/core/animation/AnimationTimeline.h
index 382aacd0360d70da485d76cb004e748d169a7447..9d3b34cd1e8d47c7dd9ad1fa8d8a4cd751bf8d98 100644
--- a/third_party/WebKit/Source/core/animation/AnimationTimeline.h
+++ b/third_party/WebKit/Source/core/animation/AnimationTimeline.h
@@ -49,7 +49,7 @@ class Document;
 class AnimationEffect;
 
 // AnimationTimeline is constructed and owned by Document, and tied to its lifecycle.
-class CORE_EXPORT AnimationTimeline final : public GarbageCollectedFinalized<AnimationTimeline>, public ScriptWrappable {
+class CORE_EXPORT AnimationTimeline : public GarbageCollectedFinalized<AnimationTimeline>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     class PlatformTiming : public GarbageCollectedFinalized<PlatformTiming> {
@@ -63,6 +63,8 @@ public:
 
     static AnimationTimeline* create(Document*, PlatformTiming* = nullptr);
 
+    virtual ~AnimationTimeline() {}
+
     void serviceAnimations(TimingUpdateReason);
     void scheduleNextService();