anchor.diff:        context.cssSource = css == null ? '' : css.content;
   
         _clearErrors();
  -
         // Analyze and run it.
         Timer.run(() {
           _performAnalysis();
  
positive.code:     gistLoader.loadGist(gistId).then((Gist gist) {
        _setGistDescription(gist.description);
        _setGistId(gist.id);
  
        GistFile dart =
            chooseGistFile(gist, ['main.dart'], (f) => f.endsWith('.dart'));
        GistFile html = chooseGistFile(gist, ['index.html', 'body.html']);
  
negative.code:       String id = url.queryParameters['id'];
        if (isLegalGistId(id)) {
          _showGist(id);
          _backupRun();
          return;
        }
      }
  