Add expandable instances and lists to the vm service.

runtime/bin/vmservice/client/lib/src/observatory_elements/instance_ref.dart

Index: runtime/bin/vmservice/client/lib/src/observatory_elements/instance_ref.dart
diff --git a/runtime/bin/vmservice/client/lib/src/observatory_elements/instance_ref.dart b/runtime/bin/vmservice/client/lib/src/observatory_elements/instance_ref.dart
index 7f5368fde62ea5962fb73b7cacb33c3134887d4e..d0dbe19ee5ea9f5b2dc986a4c187815af108d23d 100644
--- a/runtime/bin/vmservice/client/lib/src/observatory_elements/instance_ref.dart
+++ b/runtime/bin/vmservice/client/lib/src/observatory_elements/instance_ref.dart
@@ -4,6 +4,7 @@
 
 library instance_ref_element;
 
+import 'package:logging/logging.dart';
 import 'package:polymer/polymer.dart';
 import 'service_ref.dart';
 
@@ -11,10 +12,30 @@ import 'service_ref.dart';
 class InstanceRefElement extends ServiceRefElement {
   InstanceRefElement.created() : super.created();
 
+  @published bool expanded = false;
+
   String get name {
     if (ref == null) {
       return super.name;
     }
     return ref['preview'];
   }
-}
+
+  void toggleExpand(var a, var b, var c) {
+    if (expanded) {
+      ref['fields'] = null;
+      ref['elements'] = null;
+      expanded = false;
+    } else {
+      app.requestManager.requestMap(url).then((map) {
+          print(map);
+          ref['fields'] = map['fields'];
+          ref['elements'] = map['elements'];
+          ref['length'] = map['length'];
+          expanded = true;
+      }).catchError((e, trace) {
+          Logger.root.severe('Error while expanding instance-ref: $e\n$trace');
+      });
+    }
+  }
+}