Migrated test block 29 to Dart 2.0

tests/corelib_2/strings_test.dart

 // Copyright (c) 2011, 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 "package:expect/expect.dart";
 
 // Dart test program for testing class 'Strings'.
 
 class StringsTest {
   StringsTest() {}
@@ skipping 13 matching lines @@
   }
 
   static void testMain() {
     testCreation();
   }
 }
 
 main() {
   StringsTest.testMain();
 }