Attach (recommended) or Link to PDF file here:

Configuration:
- Web browser and its version: Version 81.0.4044.138 (Official Build) (32-bit)
- Operating system and its version: Windows 10
- PDF.js version: latest
- Is a browser extension: no

Steps to reproduce the problem:

1. Open https://mozilla.github.io/pdf.js/web/viewer.html
2. Open the provided document
3. ctrl + F  and search for 'costs' .
4. Search for 'costs' - match NOT found.
5. Click the 'Download' and open the file in Adobe Reader, and search for costs - match is found.

What is the expected behavior? (add screenshot)
The word 'costs' to be returned by search

What went wrong? (add screenshot)
No results found

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):  https://mozilla.github.io/pdf.js/web/viewer.html
[2001_IESC_63_5_v6.pdf](https://github.com/mozilla/pdf.js/files/4644486/2001_IESC_63_5_v6.pdf)

});
  });
  describe("PDFDataRangeTransport", function () {
    let dataPromise;
    beforeAll(function () {
      const fileName = "tracemonkey.pdf";
      dataPromise = DefaultFileReaderFactory.fetch({
        path: TEST_PDFS_PATH + fileName,
      });
    });
    afterAll(function () {
      dataPromise = null;
    });
    it("should fetch document info and page using ranges", async function () {
      const initialDataLength = 4000;
      let fetches = 0;
      const data = await dataPromise;
      const initialData = data.subarray(0, initialDataLength);
      const transport = new PDFDataRangeTransport(data.length, initialData);
      transport.requestDataRange = function (begin, end) {
        fetches++;
        waitSome(function () {
          transport.onDataProgress(4000);
          transport.onDataRange(begin, data.subarray(begin, end));
        });
      };
      const loadingTask = getDocument(transport);
      const pdfDocument = await loadingTask.promise;
      expect(pdfDocument.numPages).toEqual(14);
      const pdfPage = await pdfDocument.getPage(10);