Update to test package, make test work on dart2js.

test/wrapper_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.
 
 /// Tests wrapper utilities.
 
 import "dart:collection";
 import "package:collection/collection.dart";
-import "package:unittest/unittest.dart";
+import "package:test/test.dart";
 
 // Test that any member access/call on the wrapper object is equal to
 // an expected access on the wrapped object.
 // This is implemented by capturing accesses using noSuchMethod and comparing
 // them to expected accesses captured previously.
 
 // Compare two Invocations for having equal type and arguments.
 void testInvocations(Invocation i1, Invocation i2) {
   String name = "${i1.memberName}";
   expect(i1.isGetter, equals(i2.isGetter), reason: name);
@@ skipping 635 matching lines @@
 
     test(".retainWhere", () {
       map["f"] = "foo";
       map["b"] = "bar";
       map["q"] = "qoo";
       set.retainWhere((element) => element.endsWith("o"));
       expect(map, equals({"f": "foo", "q": "qoo"}));
     });
   });
 }