Hi pdfjs team,

Please find attach a really simple pdf file to reproduce the issue.
[Date.pdf](https://github.com/mozilla/pdf.js/files/8242310/Date.pdf)
This pdf contains 4 date fields, One with a default format (dd/mm/yyyy) and the 3 others with custom formats:

    -  dd
    -  mm
    -  yyyy

The expected behavior is that whenever I fill dd field with 16 for instance, then when i focus out that field the value displayed is 16 but I get 01.

This happens for dd field and mm but it's working fine for dd/mm/yyyy and yyyy fields.

The initial values of the pdf are properly displayed, this happens only if I focus one of those fields.

Thank you for your time

Best regards.

switch (cFormat) {
      case 0:
        return this.printd("D:yyyymmddHHMMss", oDate);
      case 1:
        return this.printd("yyyy.mm.dd HH:MM:ss", oDate);
      case 2:
        return this.printd("m/d/yy h:MM:ss tt", oDate);
    }
    const handlers = {
      mmmm: data => {
        return this._months[data.month];
      },
      mmm: data => {
        return this._months[data.month].substring(0, 3);
      },
      mm: data => {
        return (data.month + 1).toString().padStart(2, "0");
      },
      m: data => {
        return (data.month + 1).toString();
      },
      dddd: data => {
        return this._days[data.dayOfWeek];
      },
      ddd: data => {
        return this._days[data.dayOfWeek].substring(0, 3);
      },
      dd: data => {
        return data.day.toString().padStart(2, "0");