Converted Observatory refs elements

runtime/observatory/lib/src/repositories/instance.dart

 // Copyright (c) 2016, 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 repositories;
 
 class InstanceRepository extends M.InstanceRepository {
   final S.Isolate isolate;
 
   InstanceRepository(this.isolate);
 
-  Future<M.Instance> get(String id) async{
-    return (await isolate.getObject(id)) as S.Instance;
+  Future<M.Instance> get(String id, {int count: S.kDefaultFieldLimit}) async{
+    assert(count != null);
+    return (await isolate.getObject(id, count: count)) as S.Instance;
   }
 }