anchor.diff:  
   import 'dart:html';
   import 'package:polymer/polymer.dart' as polymer;
  -import 'package:ace/ace.dart' as ace;
   
   import 'spark.dart';
  +import 'lib/ace.dart';
   import 'lib/utils.dart' as utils;
   
   void main() {
  
positive.code: }
  
  class SparkPolymer extends Spark {
    List<String> _themes = [
      ace.Theme.AMBIANCE,
      ace.Theme.MONOKAI,
      ace.Theme.PASTEL_ON_DARK,
      ace.Theme.TEXTMATE,
    ];
  
    SparkPolymer() : super();
  
    @override
    void setupEditorThemes() {
      syncPrefs.getValue('aceTheme').then((String theme) {
        final int selected = (theme != null) ? _themes.indexOf(theme) : 0;
  
        (querySelector('#themeChooser') as dynamic)
          ..items = _themes.map(_beautifyThemeName)
          ..selected = selected
          ..onClick.listen(_switchTheme);
        _switchTheme();
  
negative.code:         (querySelector('#themeChooser') as dynamic).selected;
      if (selected == -1)
        selected = 0;
      final String themeName = AceEditor.THEMES[selected];
      editor.theme = themeName;
      syncPrefs.setValue('aceTheme', themeName);
    }
  
    String _beautifyThemeName(String themeName) =>
        utils.capitalize(themeName).replaceAll('_', ' ');
  }
  