Revert https://code.google.com/p/dart/source/detail?r=33346

pkg/unittest/test/unittest_async_exception_test.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.
 
 library unittestTest;
 import 'dart:isolate';
 import 'dart:async';
 import 'package:unittest/unittest.dart';
 
 part 'unittest_test_utils.dart';
 
 var testName = 'async exception test';
 
 var testFunction = (_) {
   test(testName, () {
-    expectAsync(() {});
-    _defer(() { throw "error!"; });
+    expectAsync0(() {});
+    _defer(() => guardAsync(() { throw "error!"; }));
   });
 };
 
 var expected = buildStatusString(0, 1, 0, testName, message: 'Caught error!');