rAF: Introduce FrameRequestCallbackCollection for managing rAF callbacks.

Source/core/frame/DOMWindow.h

Index: Source/core/frame/DOMWindow.h
diff --git a/Source/core/frame/DOMWindow.h b/Source/core/frame/DOMWindow.h
index 43d83667594f98a0033d07dbb4f2cbdac8550296..ed347e7f4eff11b94ce837a3f23534109f634f3f 100644
--- a/Source/core/frame/DOMWindow.h
+++ b/Source/core/frame/DOMWindow.h
@@ -26,11 +26,11 @@ class DOMWindowCSS;
 class Document;
 class Element;
 class Frame;
+class FrameRequestCallback;
 class History;
 class LocalDOMWindow;
 class MediaQueryList;
 class Navigator;
-class RequestAnimationFrameCallback;
 class Screen;
 class ScrollToOptions;
 class SerializedScriptValue;
@@ -167,8 +167,8 @@ public:
     virtual PassRefPtrWillBeRawPtr<CSSRuleList> getMatchedCSSRules(Element*, const String& pseudoElt) const = 0;
 
     // WebKit animation extensions
-    virtual int requestAnimationFrame(RequestAnimationFrameCallback*) = 0;
-    virtual int webkitRequestAnimationFrame(RequestAnimationFrameCallback*) = 0;
+    virtual int requestAnimationFrame(FrameRequestCallback*) = 0;
+    virtual int webkitRequestAnimationFrame(FrameRequestCallback*) = 0;
     virtual void cancelAnimationFrame(int id) = 0;
 
     void captureEvents() { }