Add Function based profile tree

runtime/observatory/lib/src/elements/class_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.
 
 library class_ref_element;
 
 import 'package:polymer/polymer.dart';
 import 'service_ref.dart';
 
 @CustomTag('class-ref')
 class ClassRefElement extends ServiceRefElement {
   ClassRefElement.created() : super.created();
-}
+
+  refChanged(oldValue) {
+    super.refChanged(oldValue);
+    _updateShadowDom();
+  }
+
+  void _updateShadowDom() {
+    clearShadowRoot();
+    if (ref == null) {
+      return;
+    }
+    insertLinkIntoShadowRoot(name, url, hoverText);
+  }
+}