Make server use the common protocol classes

pkg/analysis_server/test/stress/utilities/server.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.
 
 /**
  * Support for interacting with an analysis server that is running in a separate
  * process.
  */
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert' hide JsonDecoder;
 import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
+import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:path/path.dart' as path;
 
 import 'logger.dart';
 
 /**
  * Return the current time expressed as milliseconds since the epoch.
  */
 int get currentTime => new DateTime.now().millisecondsSinceEpoch;
 
 /**
@@ skipping 1047 matching lines @@
     if (buffer.length > 0) {
       buffer.writeln();
       buffer.writeln();
     }
     buffer.writeln(filePath);
     _writeErrors('  Expected ', expectedErrors);
     buffer.writeln();
     _writeErrors('  Found ', actualErrors);
   }
 }