Migrated test block 19 to Dart 2.0.

tests/corelib_2/regexp/ascii-regexp-subject_test.dart

 // Copyright (c) 2014, the Dart project authors. All rights reserved.
 // Copyright 2008 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 34 matching lines @@
     for (i = 0; i < 1000; i++) {
       re.hasMatch(s);
     }
   }
 
   repeatRegexp(new RegExp(r"^bar"));
   repeatRegexp(new RegExp(r"^foo|^bar|^baz"));
   repeatRegexp(new RegExp(r"(^bar)"));
   repeatRegexp(new RegExp(r"(?=^bar)\w+"));
 }