Roll Observatory packages and add a roll script

packages/unittest/lib/src/test_environment.dart

 // Copyright (c) 2014, 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 unittest.test_environment;
 
 import 'dart:async';
 
 import 'configuration.dart';
 import 'group_context.dart';
@@ skipping 54 matching lines @@
   /// The list of test cases to run.
   final testCases = new List<InternalTestCase>();
 
   /// The error message that is printed in the test summary.
   String uncaughtErrorMessage;
 
   TestEnvironment() {
     currentContext = rootContext;
   }
 }