anchor.diff:  
     @reflectable
     ColorPaletteCellElement get selectedCell =>
  -      cells.firstWhere((ColorPaletteCellElement e) => e.selected);
  +      cells.firstWhere((ColorPaletteCellElement e) => e.selected,
  +        orElse: () => null);
   
     @reflectable
     String get color {
  -    var c = selectedCell;
  +    final c = selectedCell;
       return (c == null) ? null : c.color;
     }
   
  
positive.code:     this.querySelectorAll('input').forEach(_initInput);
  
    void _initInput(InputElement e) {
      var attrs = e.attributes;
      if (!attrs.containsKey('type') || attrs['type'].isEmpty) e.type = 'radio';
      if (e.type != 'radio') return;
      if (_radioToPalleteCell.containsKey(e)) return;
  
negative.code:   }
  
    void _onAddCells(List<MutationRecord> recs, _) {
      final addedNodes = recs
        .expand((r) => r.addedNodes)
        .where((n) => n is Element)
        .toList(growable: false);
  