Converted Observatory context-view element

runtime/observatory/lib/src/models/objects/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 models;
 
 abstract class ContextRef extends ObjectRef {
   /// The number of variables in this context.
   int get length;
 }
 
 abstract class Context extends Object implements ContextRef {
   /// [optional] The enclosing context for this context.
   Context get parentContext;
 
   // The variables in this context object.
-  //Iterable<ContextElement> get variables;
+  Iterable<ContextElement> get variables;
 }
+
+abstract class ContextElement {
+  Guarded<InstanceRef> get value;
+}