Migrated test block 25 to Dart 2.0.

tests/corelib/regress_11099_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.
-
-void main() {
-  var l = [new MyTest(1), new MyTest(5), new MyTest(3)];
-  l.sort();
-  if (l.toString() != "[d{1}, d{3}, d{5}]") throw 'Wrong result!';
-}
-
-class MyTest implements Comparable<MyTest> {
-  final int a;
-  MyTest(this.a);
-  int compareTo(MyTest b) => this.a - b.a;
-  String toString() => "d{$a}";
-}