Converted Observatory nav-menu element

runtime/observatory/lib/elements.dart

Index: runtime/observatory/lib/elements.dart
diff --git a/runtime/observatory/lib/elements.dart b/runtime/observatory/lib/elements.dart
index d3cf333936e9b9cdb12e04f82f85b5cd197e24f0..26db5996ff6e7b98beaa2a3a9fe1fe21cffa2356 100644
--- a/runtime/observatory/lib/elements.dart
+++ b/runtime/observatory/lib/elements.dart
@@ -62,9 +62,16 @@ export 'package:observatory/src/elements/vm_view.dart';
 
 import 'dart:async';
 
+import 'package:observatory/src/elements/nav/menu.dart';
+import 'package:observatory/src/elements/nav/menu_wrapper.dart';
+
 export 'package:observatory/src/elements/helpers/rendering_queue.dart';
 
+export 'package:observatory/src/elements/nav/menu.dart';
+
 // Even though this function does not invoke any asynchronous operation
 // it is marked as async to allow future backward compatible changes.
 Future initElements() async {
+  NavMenuElement.tag.ensureRegistration();
+  NavMenuElementWrapper.tag.ensureRegistration();
 }