Migrate dart2js stubs for dart:io

tool/input_sdk/lib/io/service_object.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.
+
+part of dart.io;
+
+int _nextServiceId = 1;
+
+// TODO(ajohnsen): Use other way of getting a uniq id.
+abstract class _ServiceObject {
+  int __serviceId = 0;
+  int get _serviceId {
+    if (__serviceId == 0) __serviceId = _nextServiceId++;
+    return __serviceId;
+  }
+
+  Map _toJSON(bool ref);
+
+  String get _servicePath => "$_serviceTypePath/$_serviceId";
+
+  String get _serviceTypePath;
+
+  String get _serviceTypeName;
+
+  String _serviceType(bool ref) {
+    if (ref) return "@$_serviceTypeName";
+    return _serviceTypeName;
+  }
+}