Migrated test block 24 to Dart 2.0.

tests/corelib_2/regexp/results-cache_test.dart

 // Copyright (c) 2014, the Dart project authors. All rights reserved.
 // Copyright 2012 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 61 matching lines @@
     assertEquals(replaced, string.replaceAll(new RegExp(r"\b\w+\b"), "foo"));
   }
 
   // Check that the result is in a COW array.
   var words = string.split(" ");
   assertEquals("Friends,", words[0]);
   words[0] = "Enemies,";
   words = string.split(" ");
   assertEquals("Friends,", words[0]);
 }