Update the protocol buffer compiler plugin to use Int64 from the fixnum package

test/test_util.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.
 
 library test_util;
 
 import 'dart:typed_data';
 
+import 'package:fixnum/fixnum.dart';
 import 'package:protobuf/protobuf.dart';
 import 'package:unittest/unittest.dart';
 
 import '../out/protos/google/protobuf/unittest_import.pb.dart';
 import '../out/protos/google/protobuf/unittest.pb.dart';
 
 
-make64(lo, [hi = null]) {
+Int64 make64(lo, [hi = null]) {
   if (hi == null) hi = lo < 0 ? -1 : 0;
-  return new ByteData(8)
-      ..setUint32(0, lo, Endianness.LITTLE_ENDIAN)
-      ..setUint32(4, hi, Endianness.LITTLE_ENDIAN);
+  return new Int64.fromInts(hi, lo);
 }
 
 expect64(lo, [hi = null]) {
-  final expected = make64(lo, hi);
-  return predicate((actual) {
-    get(data, offset) => data.getUint32(offset, Endianness.LITTLE_ENDIAN);
-    return get(actual, 0) == get(expected, 0) &&
-        get(actual, 4) == get(expected, 4);
-  });
+  final Int64 expected = make64(lo, hi);
+  return predicate((Int64 actual) => actual == expected);
 }
 
 void assertAllExtensionsSet(TestAllExtensions message) {
   // TODO(antonm): introduce hasExtension matcher and other domain
   // specific ones.
   expect(message.hasExtension(Unittest.optionalInt32Extension), isTrue);
   expect(message.hasExtension(Unittest.optionalInt64Extension), isTrue);
   expect(message.hasExtension(Unittest.optionalUint32Extension), isTrue);
   expect(message.hasExtension(Unittest.optionalUint64Extension), isTrue);
   expect(message.hasExtension(Unittest.optionalSint32Extension), isTrue);
@@ skipping 1809 matching lines @@
   message.unpackedSint64.add(make64(706));
   message.unpackedFixed32.add(707);
   message.unpackedFixed64.add(make64(708));
   message.unpackedSfixed32.add(709);
   message.unpackedSfixed64.add(make64(710));
   message.unpackedFloat.add(711.0);
   message.unpackedDouble.add(712.0);
   message.unpackedBool.add(false);
   message.unpackedEnum.add(ForeignEnum.FOREIGN_BAZ);
 }