Add Function based profile tree

runtime/observatory/lib/src/elements/observatory_element.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 observatory_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
@@ skipping 79 matching lines @@
   void goto(MouseEvent event, var detail, Element target) {
     app.locationManager.onGoto(event, detail, target);
     event.stopPropagation();
   }
 
   String makeLink(String url, [ServiceObject obj]) {
     if (obj != null) {
       if (obj is Isolate) {
         url = '${url}?isolateId=${Uri.encodeComponent(obj.id)}';
       } else {
+        if (obj.id == null) {
+          // No id
+          return url;
+        }
         url = ('${url}?isolateId=${Uri.encodeComponent(obj.isolate.id)}'
-               '&objectId=${Uri.encodeComponent(obj.id)}');
+                       '&objectId=${Uri.encodeComponent(obj.id)}');
       }
     }
     return url;
   }
 
   /// Create a link that can be consumed by [goto].
   String gotoLink(String url, [ServiceObject obj]) {
     return app.locationManager.makeLink(makeLink(url, obj));
   }
 
@@ skipping 33 matching lines @@
       } else result.add(codeUnit);
     }
     if (wasTruncated) {
       result.addAll("...".codeUnits);
     } else {
       result.add("'".codeUnitAt(0));
     }
     return new String.fromCharCodes(result);
   }
 }