Merge analysis_testing package into analysis_server.

pkg/analysis_server/test/mocks2.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 testing.mocks;
 
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:typed_mock/typed_mock.dart';
@@ skipping 133 matching lines @@
   StringTypedMock(this._toString);
 
   @override
   String toString() {
     if (_toString != null) {
       return _toString;
     }
     return super.toString();
   }
 }