anchor.diff:  
   import 'dart:async';
   import 'dart:html' hide Document;
  +import 'dart:js' as js;
   
   import 'package:logging/logging.dart';
   import 'package:route_hierarchical/client.dart';
  
positive.code:   void registerResetButton() {
      if ($('[icon="refresh"]') != null) {
        _resetButton = new PaperIconButton.from($('[icon="refresh"]'));
        _resetButton.onTap.listen((_) {
          _resetDialog.toggle();
        });
      }
  
negative.code:   void registerExportButton() {
      if ($('[icon="launch"]') != null) {
        _exportButton = new PaperIconButton.from($('[icon="launch"]'));
        _exportButton.onClick.listen((_) {
          _exportDialog.toggle();
        });
      }
  