pkg/unittest: Run each test in a Zone

pkg/unittest/test/unittest_invalid_ops_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 = 'invalid ops throw while test is running';
 
 var testFunction = (_) {
   test(testName, () {
     expect(() => test('test', () {}), throwsStateError);
     expect(() => solo_test('test', () {}), throwsStateError);
     expect(() => group('test', () {}), throwsStateError);
     expect(() => solo_group('test', () {}), throwsStateError);
     expect(() => setUp(() {}), throwsStateError);
     expect(() => tearDown(() {}), throwsStateError);
     expect(() => runTests(), throwsStateError);
-    expect(() => rerunTests(), throwsStateError);
   });
 };
 
 var expected = buildStatusString(1, 0, 0, testName);