Use HasToJson when set Reponse/Notification parameters.

pkg/analysis_server/lib/src/search/search_domain.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 search.domain;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/search/element_references.dart';
@@ skipping 96 matching lines @@
       return exception.response;
     }
     return null;
   }
 
   void _sendSearchNotification(String searchId, bool isLast,
       List<SearchResult> results) {
     Notification notification = new Notification(SEARCH_RESULTS);
     notification.setParameter(ID, searchId);
     notification.setParameter(LAST, isLast);
-    notification.setParameter(
-        RESULTS,
-        results.map(SearchResult.asJson).toList());
+    notification.setParameter(RESULTS, results);
     server.sendNotification(notification);
   }
 }