Improve Code object support in service and observatory

runtime/bin/vmservice/client/lib/src/observatory_elements/code_view.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 code_view_element;
 
 import 'package:polymer/polymer.dart';
+import 'package:observatory/observatory.dart';
 import 'observatory_element.dart';
 
 @CustomTag('code-view')
 class CodeViewElement extends ObservatoryElement {
-  @published Map code = toObservable({});
+  @published Code code;
   CodeViewElement.created() : super.created();
 
   String get cssPanelClass {
-    if (code != null && code['is_optimized'] != null) {
-      return 'panel panel-success';
-    }
-    return 'panel panel-warning';
+    return 'panel panel-success';
   }
 }