Introduce WindowTimers IDL interface

Source/core/page/Window.idl

Index: Source/core/page/Window.idl
diff --git a/Source/core/page/Window.idl b/Source/core/page/Window.idl
index 1ea2bb8e7e867f6f913daf5eb44093227e76d76b..d4682308380b5cac4dca09987ab1bea96f7969a2 100644
--- a/Source/core/page/Window.idl
+++ b/Source/core/page/Window.idl
@@ -161,12 +161,6 @@
 
     [Replaceable] readonly attribute Performance performance;
 
-    // Timers
-    [Custom] long setTimeout(any handler, [Default=Undefined] optional long timeout);
-    void clearTimeout([Default=Undefined] optional long handle);
-    [Custom] long setInterval(any handler, [Default=Undefined] optional long timeout);
-    void clearInterval([Default=Undefined] optional long handle);
-
     [MeasureAs=UnprefixedRequestAnimationFrame] long requestAnimationFrame(RequestAnimationFrameCallback callback);
     void cancelAnimationFrame(long id);
     [MeasureAs=PrefixedRequestAnimationFrame] long webkitRequestAnimationFrame(RequestAnimationFrameCallback callback);
@@ -314,3 +308,5 @@
     [Custom, NotEnumerable] getter Window (DOMString name);
 };
 
+Window implements WindowTimers;
+