Add --hot-reload-rollback test mode

tools/testing/dart/test_options.dart

 // Copyright (c) 2013, 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.
 
 library test_options_parser;
 
 import "dart:io";
 import "drt_updater.dart";
 import "test_suite.dart";
 import "path.dart";
@@ skipping 172 matching lines @@
           [],
           false,
           type: 'bool'),
       new _TestOptionSpecification(
           'noopt', 'Run an in-place precompilation', ['--noopt'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
           'hot_reload', 'Run hot reload stress tests', ['--hot-reload'], [],
           false, type: 'bool'),
       new _TestOptionSpecification(
+          'hot_reload_rollback',
+          'Run hot reload rollback stress tests', ['--hot-reload-rollback'],
+          [],
+          false, type: 'bool'),
+      new _TestOptionSpecification(
           'use_blobs',
           'Use mmap instead of shared libraries for precompilation',
           ['--use-blobs'], [], false, type: 'bool'),
       new _TestOptionSpecification(
           'timeout', 'Timeout in seconds', ['-t', '--timeout'], [], -1,
           type: 'int'),
       new _TestOptionSpecification(
           'progress',
           'Progress indication mode',
           ['-p', '--progress'],
@@ skipping 701 matching lines @@
       if (option.keys.contains(name)) {
         return option;
       }
     }
     print('Unknown test option $name');
     exit(1);
   }
 
   List<_TestOptionSpecification> _options;
 }