Observatory: Fix instance view of lists.

runtime/observatory/lib/src/elements/helpers/any_ref.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.
 
 import 'dart:html';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/src/elements/class_ref.dart';
 import 'package:observatory/src/elements/code_ref.dart';
 import 'package:observatory/src/elements/context_ref.dart';
 import 'package:observatory/src/elements/error_ref.dart';
@@ skipping 10 matching lines @@
 import 'package:observatory/src/elements/pc_descriptors_ref.dart';
 import 'package:observatory/src/elements/script_ref.dart';
 import 'package:observatory/src/elements/sentinel_value.dart';
 import 'package:observatory/src/elements/type_arguments_ref.dart';
 import 'package:observatory/src/elements/token_stream_ref.dart';
 import 'package:observatory/src/elements/unknown_ref.dart';
 
 Element anyRef(M.IsolateRef isolate, ref,
     M.InstanceRepository instances, {RenderingQueue queue}) {
   if (ref is M.Guarded) {
-    return anyRef(isolate, ref.asSentinel ?? ref.asValue, instances,
-        queue: queue);
+    if (ref.isSentinel) {
+      return anyRef(isolate, ref.asSentinel, instances, queue: queue);
+    } else {
+      return anyRef(isolate, ref.asValue, instances, queue: queue);
+    }
   } else if (ref is M.ObjectRef) {
     if (ref is M.ClassRef) {
       return new ClassRefElement(isolate, ref, queue: queue);
     } else if (ref is M.CodeRef) {
       return new CodeRefElement(isolate, ref, queue: queue);
     } else if (ref is M.ContextRef) {
       return new ContextRefElement(isolate, ref, queue: queue);
     } else if (ref is M.Error ) {
       return new ErrorRefElement(ref, queue: queue);
     } else if (ref is M.FieldRef) {
@@ skipping 22 matching lines @@
       return new TokenStreamRefElement(isolate, ref, queue: queue);
     } else if (ref is M.UnknownObjectRef) {
       return new UnknownObjectRefElement(isolate, ref, queue: queue);
     } else {
       return new AnchorElement(href: Uris.inspect(isolate, object: ref))
         ..text = 'object';
     }
   } else if (ref is M.Sentinel) {
     return new SentinelValueElement(ref, queue: queue);
   }
-  throw new Exception('Unknown runtimeType (${ref.runtimeType})');
+  throw new Exception('Unknown ref type (${ref.runtimeType})');
 }