Removed const from classes arrays in Observatory

runtime/observatory/lib/src/elements/isolate/counter_chart.dart

 // Copyright (c) 2016, 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:charted/charted.dart';
 import "package:charted/charts/charts.dart";
 import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
 import 'package:observatory/src/elements/helpers/tag.dart';
@@ skipping 37 matching lines @@
 
   static final _columns = [
     new ChartColumnSpec(label: 'Type', type: ChartColumnSpec.TYPE_STRING),
     new ChartColumnSpec(label: 'Percent', formatter: (v) => v.toString())
   ];
 
   void render() {
     final _series = [new ChartSeries("Work", const [1], new PieChartRenderer(
       sortDataByValue: false
     ))];
-    final areaHost = new DivElement()..classes = const ['host'];
-    final  legendHost = new DivElement()..classes = const ['legend'];
+    final areaHost = new DivElement()..classes = ['host'];
+    final  legendHost = new DivElement()..classes = ['legend'];
     children = [areaHost, legendHost];
     final rect = areaHost.getBoundingClientRect();
     final minSize = new Rect.size(rect.width, rect.height);
     final config = new ChartConfig(_series, const [0])
         ..minimumSize = minSize
         ..legend = new ChartLegend(legendHost, showValues: true);
     final data = new ChartData(_columns, _counters.keys
           .map((key) => [key, double.parse(_counters[key].split('%')[0])])
           .toList());
 
     new LayoutArea(areaHost, data, config, state: new ChartState(),
         autoUpdate: false)
       ..addChartBehavior(new Hovercard())
       ..addChartBehavior(new AxisLabelTooltip())
       ..draw();
   }
 }