Roll Observatory packages and add a roll script

packages/unittest/lib/src/expected_function.dart

 // Copyright (c) 2015, 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.expected_function;
 
 import '../unittest.dart';
 
 import 'internal_test_case.dart';
 
@@ skipping 183 matching lines @@
     if (_complete) return;
     if (_minExpectedCalls > 0 && _actualCalls < _minExpectedCalls) return;
     if (_isDone != null && !_isDone()) return;
 
     // Mark this callback as complete and remove it from the test case's
     // oustanding callback count; if that hits zero the test is done.
     _complete = true;
     _testCase.markCallbackComplete();
   }
 }