Adjust debugging statements for ie11.

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 13 matching lines @@
     entry = _nextCallback = entry.next;
   }
   // Any new callback must register a callback function now.
   _lastCallback = null;
 }
 
 void _asyncRunCallback() {
   try {
     _asyncRunCallbackLoop();
   } catch (e) {
+    print('microtask error $e'); // TODO(efortuna): Remove this.
     _AsyncRun._scheduleImmediate(_asyncRunCallback);
     _nextCallback = _nextCallback.next;
     rethrow;
   }
 }
 
 void _scheduleAsyncCallback(callback) {
   // Optimizing a group of Timer.run callbacks to be executed in the
   // same Timer callback.
   if (_lastCallback == null) {
@@ skipping 37 matching lines @@
     return;
   }
   Zone.current.scheduleMicrotask(
       Zone.current.bindCallback(callback, runGuarded: true));
 }
 
 class _AsyncRun {
   /** Schedule the given callback before any other event in the event-loop. */
   external static void _scheduleImmediate(void callback());
 }