Fix unittest for dart2js.

pkg/unittest/test/pretty_print_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.
 
 import 'dart:collection';
 
 import 'package:unittest/src/pretty_print.dart';
 import 'package:unittest/unittest.dart';
 
 class DefaultToString {}
 
 class CustomToString {
   String toString() => "string representation";
 }
 
 class _PrivateName {
   String toString() => "string representation";
 }
 
 class _PrivateNameIterable extends IterableMixin {
   Iterator get iterator => [1, 2, 3].iterator;
 }
 
 void main() {
   test('with primitive objects', () {
     expect(prettyPrint(12), equals('<12>'));
     expect(prettyPrint(12.13), equals('<12.13>'));
     expect(prettyPrint(true), equals('<true>'));
     expect(prettyPrint(null), equals('<null>'));
-    expect(prettyPrint(() => 12), equals('<Closure: (dynamic) => dynamic>'));
+    expect(prettyPrint(() => 12),
+        matches(r'<Closure(: \(dynamic\) => dynamic)?>'));
   });
 
   test('with an object with a default [toString]', () {
     expect(prettyPrint(new DefaultToString()),
         equals("<Instance of 'DefaultToString'>"));
   });
 
   test('with an object with a custom [toString]', () {
     expect(prettyPrint(new CustomToString()),
         equals('CustomToString:<string representation>'));
@@ skipping 171 matching lines @@
       expect(prettyPrint({'0': 1, '2': 3, '4': 5, '6': 7}, maxItems: 4),
           equals("{'0': 1, '2': 3, '4': 5, '6': 7}"));
     });
 
     test("that's over maxItems", () {
       expect(prettyPrint({'0': 1, '2': 3, '4': 5, '6': 7}, maxItems: 3),
           equals("{'0': 1, '2': 3, ...}"));
     });
   });
 }