Make Zone API strong mode clean.

tools/dom/templates/html/impl/impl_Window.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of $LIBRARYNAME;
 
 @DocsEditable()
 $if DART2JS
 $(ANNOTATIONS)@Native("Window,DOMWindow")
 $(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
@@ skipping 97 matching lines @@
    * request. This value only needs to be saved if you intend to call
    * [cancelAnimationFrame] so you can specify the particular animation to
    * cancel.
    *
    * Note: The supplied [callback] needs to call [requestAnimationFrame] again
    * for the animation to continue.
    */
   @DomName('Window.requestAnimationFrame')
   int requestAnimationFrame(FrameRequestCallback callback) {
     _ensureRequestAnimationFrame();
-    return _requestAnimationFrame(_wrapZone/*<num, dynamic>*/(callback));
+    return _requestAnimationFrame(_wrapZone(callback));
   }
 
   /**
    * Cancels an animation frame request.
    *
    * ## Other resources
    *
    * * [Window.cancelAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/Window.cancelAnimationFrame)
    *   from MDN.
    */
@@ skipping 246 matching lines @@
       {bool useCapture: false}) {
 $if DART2JS
     // Specify the generic type for _ElementEventStreamImpl only in dart2js to
     // avoid checked mode errors in dartium.
     return new _ElementListEventStreamImpl<BeforeUnloadEvent>(e, _eventType, useCapture);
 $else
     return new _ElementListEventStreamImpl(e, _eventType, useCapture);
 $endif
   }
 }