Fix the tests.

test/peer_test.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.
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
@@ skipping 156 matching lines @@
       var incomingController = new StreamController();
       var outgoingController = new StreamController();
       var jsonPeer = new json_rpc.Peer(
           new StreamChannel(incomingController.stream, outgoingController));
 
       expect(outgoingController.stream.first.then(JSON.decode), completion({
         "jsonrpc": "2.0",
         "error": {
           'code': error_code.PARSE_ERROR,
           "message": startsWith("Invalid JSON: "),
-          "data": {'request': '{invalid'}
+          // TODO(nweiz): Always expect the source when sdk#25655 is fixed.
+          "data": {'request': anyOf([isNull, '{invalid'])}
         },
         "id": null
       }));
 
       jsonPeer.listen();
 
       incomingController.add("{invalid");
     });
 
     test("returns a response for incorrectly-structured JSON", () {
       expect(outgoing.first, completion({
         "jsonrpc": "2.0",
         "error": {
           'code': error_code.INVALID_REQUEST,
           "message": 'Request must contain a "jsonrpc" key.',
           "data": {'request': {'completely': 'wrong'}}
         },
         "id": null
       }));
 
       peer.listen();
 
       incoming.add({
         "completely": "wrong"
       });
     });
   });
 }