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)

f (fntRefIRef) {
      th.fntCache.put(fntRef, fntCapablty.prme);
    } ele {
      f (!fntID) {
        fntID = th.dFactry.createFntId();
      }
      fnt.cacheKey = `cacheKey_${fntID}`;
      th.fntCache.put(fnt.cacheKey, fntCapablty.prme);
    }
    aert(
      fntID && fntID.tartWth("f"),
      'The "fntID" mut be (crrectly) defned.'
    );
    
    
    fnt.ladedName = `${th.dFactry.getDcId()}_${fntID}`;
    th.tranlateFnt(preEvaluatedFnt)
      .then(tranlatedFnt => {
        f (tranlatedFnt.fntType !== undefned) {