Implement requestIdleCallback API

Source/core/frame/LocalDOMWindow.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 126 matching lines @@
     void moveBy(int x, int y) const override;
     void moveTo(int x, int y) const override;
     void resizeBy(int x, int y) const override;
     void resizeTo(int width, int height) const override;
     PassRefPtrWillBeRawPtr<MediaQueryList> matchMedia(const String&) override;
     PassRefPtrWillBeRawPtr<CSSStyleDeclaration> getComputedStyle(Element*, const String& pseudoElt) const override;
     PassRefPtrWillBeRawPtr<CSSRuleList> getMatchedCSSRules(Element*, const String& pseudoElt) const override;
     int requestAnimationFrame(FrameRequestCallback*) override;
     int webkitRequestAnimationFrame(FrameRequestCallback*) override;
     void cancelAnimationFrame(int id) override;
+    int requestIdleCallback(IdleRequestCallback*, double timeoutMillis) override;
+    void cancelIdleCallback(int id) override;
     void schedulePostMessage(PassRefPtrWillBeRawPtr<MessageEvent>, LocalDOMWindow* source, SecurityOrigin* target, PassRefPtrWillBeRawPtr<ScriptCallStack> stackTrace);
 
     void registerProperty(DOMWindowProperty*);
     void unregisterProperty(DOMWindowProperty*);
 
     void reset();
 
     unsigned pendingUnloadEventListeners() const;
 
     bool allowPopUp(); // Call on first window, not target window.
@@ skipping 127 matching lines @@
 }
 
 inline String LocalDOMWindow::defaultStatus() const
 {
     return m_defaultStatus;
 }
 
 } // namespace blink
 
 #endif // LocalDOMWindow_h