Converted Observatory context-view element

runtime/observatory/lib/src/repositories/context.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 PortsRepository implements M.PortsRepository {
-  Future<M.Ports> get(M.IsolateRef i) async {
+class ContextRepository extends M.ContextRepository {
+  ContextRepository();
+
+  Future<M.Context> get(M.IsolateRef i, String id) async{
     S.Isolate isolate = i as S.Isolate;
     assert(isolate != null);
-    final response = await isolate.invokeRpc('_getPorts', {});
-    return new S.Ports(response);
+    return (await isolate.getObject(id)) as S.Context;
   }
 }