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.

/* Copyright 2020 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { loadScript } from "../../src/display/display_utils.js";
const sandboxBundleSrc = "../../build/generic/build/pdf.sandbox.js";
describe("Scripting", function () {
  let sandbox, send_queue, test_id, ref, windowAlert;
  function getId() {
    const id = `${ref++}R`;
    return id;
  }
  function myeval(code) {
    const key = (test_id++).toString();
    return sandbox.eval(code, key).then(() => {
      const result = send_queue.get(key).result;
      send_queue.delete(key);