code: function isDayFirst() {
      if (dayFirst !== null) {
        return dayFirst;
      }
  
      var formatter = makeFormatter({day: 'numeric', month: 'short'});
      if (formatter) {
        var output = formatter.format(new Date(0));
        dayFirst = !!output.match(/^\d/);
        return dayFirst;
      } else {
        return false;
      }
    }
docs: Private: Determine if the day should be formatted before the month name in the user's current locale. For example, `9 Jun` for en-GB and `Jun 9` for en-US.  Returns true if the day appears before the month.