Animations: Introduce compositor AnimationPlayer and AnimationTimeline.

Source/web/WebFrameWidgetImpl.h

Index: Source/web/WebFrameWidgetImpl.h
diff --git a/Source/web/WebFrameWidgetImpl.h b/Source/web/WebFrameWidgetImpl.h
index de5bfe413d20c230c5001edbe7e3e75311c3fc1b..ce056006e6724908ca59c6e6905521090fb87df2 100644
--- a/Source/web/WebFrameWidgetImpl.h
+++ b/Source/web/WebFrameWidgetImpl.h
@@ -48,6 +48,7 @@ class LocalFrame;
 class Page;
 class LayerCompositor;
 class UserGestureToken;
+class WebCompositorAnimationTimeline;
 class WebLayer;
 class WebLayerTreeView;
 class WebLocalFrameImpl;
@@ -133,6 +134,7 @@ public:
     LayerCompositor* compositor() const;
     void suppressInvalidations(bool enable);
     void setRootGraphicsLayer(GraphicsLayer*);
+    void setCompositorAnimationTimeline(WebCompositorAnimationTimeline*);
 
     void setVisibilityState(WebPageVisibilityState, bool) override;