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.

const value1 = this.AFMakeNumber(nValue1);
    if (value1 === null) {
      throw new Error("Invalid nValue1 in AFSimple");
    }
    const value2 = this.AFMakeNumber(nValue2);
    if (value2 === null) {
      throw new Error("Invalid nValue2 in AFSimple");
    }
    switch (cFunction) {
      case "AVG":
        return (value1 + value2) / 2;
      case "SUM":
        return value1 + value2;
      case "PRD":
        return value1 * value2;
      case "MIN":
        return Math.min(value1, value2);
      case "MAX":
        return Math.max(value1, value2);
    }
    throw new Error("Invalid cFunction in AFSimple");
  }
  AFSimple_Calculate(cFunction, cFields) {