Do not JSON encode the 'result' of a service rpc.

runtime/bin/vmservice/server.dart

 // Copyright (c) 2013, 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.
 
 part of vmservice_io;
 
 class WebSocketClient extends Client {
   static const int PARSE_ERROR_CODE = 4000;
   static const int BINARY_MESSAGE_ERROR_CODE = 4001;
   static const int NOT_MAP_ERROR_CODE = 4002;
@@ skipping 17 matching lines @@
         socket.close(NOT_MAP_ERROR_CODE, 'Message must be a JSON map.');
         return;
       }
       var serial = map['id'];
       onMessage(serial, new Message.fromJsonRpc(map));
     } else {
       socket.close(BINARY_MESSAGE_ERROR_CODE, 'Message must be a string.');
     }
   }
 
-  void post(var serial, dynamic result) {
+  void post(dynamic result) {
     try {
-      if (serial == null && result is! String) {
-        socket.add(result);
-      } else {
-        Map map = {
-          'id': serial,
-          'result': result
-        };
-        socket.add(JSON.encode(map));
-      }
+      socket.add(result);
     } catch (_) {
       print("Ignoring error posting over WebSocket.");
     }
   }
 
   dynamic toJson() {
     Map map = super.toJson();
     map['type'] = 'WebSocketClient';
     map['socket'] = '$socket';
     return map;
   }
 }
 
 
 class HttpRequestClient extends Client {
   static ContentType jsonContentType =
       new ContentType("application", "json", charset: "utf-8");
   final HttpRequest request;
 
   HttpRequestClient(this.request, VMService service)
       : super(service, sendEvents:false);
 
-  void post(var serial, String result) {
+  void post(String result) {
     request.response..headers.contentType = jsonContentType
                     ..write(result)
                     ..close();
     close();
   }
 
   dynamic toJson() {
     Map map = super.toJson();
     map['type'] = 'HttpRequestClient';
     map['request'] = '$request';
@@ skipping 128 matching lines @@
       print('Could not shutdown Observatory HTTP server:\n$e\n$st\n');
       _notifyServerState("", 0);
       return this;
     });
   }
 
 }
 
 void _notifyServerState(String ip, int port)
     native "VMServiceIO_NotifyServerState";