Migrated test block 24 to Dart 2.0.

tests/corelib_2/regexp/unicode-handling_test.dart

 // Copyright (c) 2014, the Dart project authors. All rights reserved.
 // Copyright 2013 the V8 project authors. All rights reserved.
 // Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 // 1.  Redistributions of source code must retain the above copyright
 //     notice, this list of conditions and the following disclaimer.
 // 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 55 matching lines @@
   var inlineRe = new RegExp(r".m\u2820p");
   assertEquals(inlineRe.firstMatch(sample).group(0), 'bm\u2820p');
 
   // Test handling of \u007c "|"
   var bsample = "sample bm\u007cp cm\\u007cp";
 
   var binlineRe = new RegExp(r".m\u007cp");
 
   assertEquals(binlineRe.firstMatch(bsample).group(0), 'bm|p');
 }