Give instances their own model class; move DartErrors out of instance-ref into their own error-ref.

runtime/bin/vmservice/observatory/lib/src/elements/inbound_reference.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.
 
 library inbound_reference_element;
 
 import 'dart:async';
 import 'package:polymer/polymer.dart';
 import 'package:observatory/service.dart';
 import 'service_ref.dart';
 
 @CustomTag('inbound-reference')
 class InboundReferenceElement extends ServiceRefElement {
+  @published ObservableMap ref;

[Cutch, 2014/08/28 14:46:05]

ServiceMap

[rmacnak, 2014/08/28 19:41:05]

We don't get a ServiceMap here for some reason.

   InboundReferenceElement.created() : super.created();
 
   dynamic get slot => ref['slot'];
   bool get slotIsArrayIndex => slot is num;
   bool get slotIsField => slot is ServiceMap && slot['type'] == '@Field';
 
   ServiceObject get source => ref['source'];
 
   // I.e., inbound references to 'source' for recursive pointer chasing.
   @observable ObservableList inboundReferences;
   Future<ServiceObject> fetchInboundReferences(arg) {
     return source.isolate.get(source.id + "/inbound_references?limit=$arg")
         .then((ServiceMap response) {
           inboundReferences = new ObservableList.from(response['references']);
         });
   }
 
   // TODO(turnidge): This is here to workaround vm/dart2js differences.
   dynamic expander() {
     return expandEvent;
   }
- 
+
   void expandEvent(bool expand, var done) {
     assert(ref is ServiceMap);
     if (expand) {
       fetchInboundReferences(100).then((result) {
         notifyPropertyChange(#ref, 0, 1);
       }).whenComplete(done);
     } else {
-      ServiceMap refMap = ref;
-      refMap['fields'] = null;
-      refMap['elements'] = null;
+      inboundReferences = null;
       done();
     }
   }
 }