Removed const from classes arrays in Observatory

runtime/observatory/lib/src/elements/sentinel_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.
 
 import 'dart:html';
 import 'dart:async';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
 import 'package:observatory/src/elements/helpers/tag.dart';
 import 'package:observatory/src/elements/nav/bar.dart';
@@ skipping 67 matching lines @@
   void render() {
     children = [
       new NavBarElement(queue: _r.queue)
         ..children = [
           new NavTopMenuElement(queue: _r.queue),
           new NavVMMenuElement(_vm, _events, queue: _r.queue),
           new NavIsolateMenuElement(_isolate, _events, queue: _r.queue),
           new NavMenuElement('sentinel', last: true, queue: _r.queue),
           new NavNotifyElement(_notifications, queue: _r.queue)
         ],
-      new DivElement()..classes = const ['content-centered-big']
+      new DivElement()..classes = ['content-centered-big']
         ..children = [
           new HeadingElement.h2()
             ..text = 'Sentinel: #{_sentinel.valueAsString}',
           new HRElement(),
           new DivElement()
             ..text = _sentinelKindToDescription(_sentinel.kind),
           new HRElement(),
           new ViewFooterElement(queue: _r.queue)
         ]
     ];
@@ skipping 14 matching lines @@
       case M.SentinelKind.optimizedOut:
         return 'This object is no longer needed and has been removed by the '
                'optimizing compiler.';
       case M.SentinelKind.free:
         return '';
     }
     throw new Exception('Unknown SentinelKind: $kind');
   }
 
 }