Remove AsyncError with Expando.

tools/testing/dart/test_suite.dart

 // 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.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 61 matching lines @@
    * marked as completed, otherwise you'll get an exception indicating that a
    * future has already been completed).
    */
   void add(Future task) {
     if (_pending == _FINISHED) {
       throw new Exception("FutureFutureAlreadyCompleteException");
     }
     _pending++;
     var handledTaskFuture = task.catchError((e) {
       if (!wasCompleted) {
-        _completer.completeError(e.error, e.stackTrace);
+        _completer.completeError(e);
         wasCompleted = true;
       }
     }).then((_) {
       _pending--;
       if (_pending == 0) {
         _pending = _FINISHED;
         if (!wasCompleted) {
           _completer.complete(futures);
           wasCompleted = true;
         }
@@ skipping 1845 matching lines @@
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
  * $compileErrorSkip tests are skipped on browsers due to compile-time error
 """;
     print(report);
    }
 }