Implement requestIdleCallback API

Source/core/frame/LocalDOMWindow.cpp

Index: Source/core/frame/LocalDOMWindow.cpp
diff --git a/Source/core/frame/LocalDOMWindow.cpp b/Source/core/frame/LocalDOMWindow.cpp
index 3f052418afcb3beefa9ca0a011a9b52324478bac..ffba1f8008809cf24919a52ef67aa83ca3251dac 100644
--- a/Source/core/frame/LocalDOMWindow.cpp
+++ b/Source/core/frame/LocalDOMWindow.cpp
@@ -1264,23 +1264,36 @@ void LocalDOMWindow::resizeTo(int width, int height) const
 int LocalDOMWindow::requestAnimationFrame(FrameRequestCallback* callback)
 {
     callback->m_useLegacyTimeBase = false;
-    if (Document* d = document())
-        return d->requestAnimationFrame(callback);
+    if (document())
+        return document()->requestAnimationFrame(callback);
     return 0;
 }
 
 int LocalDOMWindow::webkitRequestAnimationFrame(FrameRequestCallback* callback)
 {
     callback->m_useLegacyTimeBase = true;
-    if (Document* d = document())
-        return d->requestAnimationFrame(callback);
+    if (document())
+        return document()->requestAnimationFrame(callback);
     return 0;
 }
 
 void LocalDOMWindow::cancelAnimationFrame(int id)
 {
-    if (Document* d = document())
-        d->cancelAnimationFrame(id);
+    if (document())
+        document()->cancelAnimationFrame(id);
+}
+
+int LocalDOMWindow::requestIdleCallback(IdleRequestCallback* callback, double timeout)
+{
+    if (document())
+        return document()->requestIdleCallback(callback, timeout);
+    return 0;
+}
+
+void LocalDOMWindow::cancelIdleCallback(int id)
+{
+    if (document())
+        document()->cancelIdleCallback(id);
 }
 
 bool LocalDOMWindow::addEventListener(const AtomicString& eventType, PassRefPtr<EventListener> prpListener, bool useCapture)