Rework the replay test to be more correct

pkg/analysis_server/lib/plugin/protocol/protocol.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.
 
 /**
  * Support for client code that needs to interact with the requests, responses
  * and notifications that are part of the analysis server's wire protocol.
  */
 library analysis_server.plugin.protocol.protocol;
 
@@ skipping 549 matching lines @@
   /**
    * Initialize a newly created instance to represent an error condition caused
    * by a [request] for a service that is not supported.
    */
   Response.unsupportedFeature(String requestId, String message)
       : this(requestId,
             error: new RequestError(
                 RequestErrorCode.UNSUPPORTED_FEATURE, message));
 
   /**
+   * Return a table mapping the names of result fields to their values.  Should
+   * be `null` if there is no result to send.
+   */
+  Map<String, Object> get result => _result;
+
+  /**
    * Return a table representing the structure of the Json object that will be
    * sent to the client to represent this response.
    */
   Map<String, Object> toJson() {
     Map<String, Object> jsonObject = new HashMap<String, Object>();
     jsonObject[ID] = id;
     if (error != null) {
       jsonObject[ERROR] = error.toJson();
     }
     if (_result != null) {
       jsonObject[RESULT] = _result;
     }
     return jsonObject;
   }
 }