Always serialize 64-bit integers as strings in JSON.

test/event_test.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.
 
 /// Tests event delivery using PbEventMixin.
 library event_test;
 
 import 'dart:typed_data' show Uint8List;
 
 import 'package:protobuf/protobuf.dart'
     show GeneratedMessage, Extension, ExtensionRegistry, PbFieldType;
 import 'package:protobuf/src/protobuf/mixins/event_mixin.dart'
     show PbEventMixin, PbFieldChange;
 import 'package:test/test.dart' show test, expect;
 
 import 'mock_util.dart' show MockMessage, mockInfo;
 
 class Rec extends MockMessage with PbEventMixin {
   get info_ => _info;
   static final _info = mockInfo("Rec", () => new Rec());
 }
 
-Extension comment = new Extension("Rec", "comment", 5, PbFieldType.OS);
+Extension comment = new Extension("Rec", "comment", 6, PbFieldType.OS);
 
 main() {
   test('Events are sent when setting and clearing a non-repeated field', () {
     var log = makeLog();
     var r = new Rec();
     r.changes.listen((List<PbFieldChange> changes) {
       log.add(changes);
     });
 
     r.val = 123;
@@ skipping 183 matching lines @@
     clear(String expected) {
       r.clear();
       r.deliverChanges();
       checkLogOnce(log, [tag, expected, ""]);
     }
 
     setComment("hello");
     clear("hello");
 
     setComment("hello");
-    r.setField(5, "hi");
+    r.setField(6, "hi");
     r.deliverChanges();
     checkLogOnce(log, [tag, "hello", "hi"]);
     clear("hi");
 
     setComment("hello");
     r.clearExtension(comment);
     r.deliverChanges();
     checkLogOnce(log, [tag, "hello", ""]);
 
     setComment("hello");
@@ skipping 53 matching lines @@
 
 List toTuple(PbFieldChange fc) {
   fixValue(v) {
     if (v is GeneratedMessage) {
       return "<msg>";
     }
     return v;
   }
   return [fc.tag, fixValue(fc.oldValue), fixValue(fc.newValue)];
 }