Small cleanup to Code and Profiler pages

runtime/bin/vmservice/client/lib/src/elements/isolate_profile.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 isolate_profile_element;
 
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:logging/logging.dart';
 import 'package:observatory/service.dart';
@@ skipping 63 matching lines @@
       if (!shouldDisplayChild(childNode, threshold)) {
         continue;
       }
       var row = new ProfileCodeTrieNodeTreeRow(profile, root, childNode, this);
       children.add(row);
     }
   }
 
   void onHide() {
   }
+
+  bool hasChildren() {
+    return node.children.length > 0;
+  }
 }
 
 /// Displays an IsolateProfile
 @CustomTag('isolate-profile')
 class IsolateProfileElement extends ObservatoryElement {
   IsolateProfileElement.created() : super.created();
   @published ServiceMap profile;
   @observable bool hideTagsChecked;
   @observable String sampleCount = '';
   @observable String refreshTime = '';
@@ skipping 96 matching lines @@
     if (row is TableRowElement) {
       // Subtract 1 to get 0 based indexing.
       try {
         tree.toggle(row.rowIndex - 1);
       }  catch (e, stackTrace) {
         Logger.root.warning('toggleExpanded', e, stackTrace);
       }
     }
   }
 }