Migrated test block 19 to Dart 2.0.

tests/corelib_2/regexp/captures_test.dart

 // Copyright (c) 2014, the Dart project authors. All rights reserved.
 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
@@ skipping 17 matching lines @@
 
 import 'v8_regexp_utils.dart';
 import 'package:expect/expect.dart';
 
 void main() {
   var re = new RegExp(
       r"^(((N({)?)|(R)|(U)|(V)|(B)|(H)|(n((n)|(r)|(v)|(h))?)|(r(r)?)|(v)|(b((n)|(b))?)|(h))|((Y)|(A)|(E)|(o(u)?)|(p(u)?)|(q(u)?)|(s)|(t)|(u)|(w)|(x(u)?)|(y)|(z)|(a((T)|(A)|(L))?)|(c)|(e)|(f(u)?)|(g(u)?)|(i)|(j)|(l)|(m(u)?)))+");
   var str = "Avtnennan gunzvmu pubExnY nEvln vaTxh rmuhguhaTxnY";
   assertTrue(re.hasMatch(str));
 }