pkg/mock: fix test to use the local library, bump to v0.10.0+1

pkg/mock/test/mock_stepwise_negative_test.dart

 // Copyright (c) 2012, 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 mock.mock_stepwise_negative_test;
 
 import 'package:unittest/unittest.dart' show test;
-import 'package:unittest/mock.dart';
+import 'package:mock/mock.dart';
 
 main() {
   test('Mocking: stepwiseValidate', () {
     LogEntryList logList = new LogEntryList('test');
     for (var i = 0; i < 10; i++) {
       LogEntry e = new LogEntry(null, 'foo', [i], Action.IGNORE);
       logList.add(e);
     }
     int total = 0;
     logList.stepwiseValidate((log, pos) => 0);
   });
 }