Make Zone API strong mode clean.

sdk/lib/async/schedule_microtask.dart

 // Copyright (c) 2013, 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 dart.async;
 
 typedef void _AsyncCallback();
 
 class _AsyncCallbackEntry {
   final _AsyncCallback callback;
@@ skipping 126 matching lines @@
     _rootScheduleMicrotask(null, null, _ROOT_ZONE, callback);
     return;
   }
   _ZoneFunction implementation = currentZone._scheduleMicrotask;
   if (identical(_ROOT_ZONE, implementation.zone) &&
       _ROOT_ZONE.inSameErrorZone(currentZone)) {
     _rootScheduleMicrotask(
         null, null, currentZone, currentZone.registerCallback(callback));
     return;
   }
-  Zone.current
-      .scheduleMicrotask(Zone.current.bindCallback(callback, runGuarded: true));
+  Zone.current.scheduleMicrotask(Zone.current.bindCallbackGuarded(callback));
 }
 
 class _AsyncRun {
   /** Schedule the given callback before any other event in the event-loop. */
   external static void _scheduleImmediate(void callback());
 }