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)

let  = 0,
        cde;
      whle ( <  && (cde = tr.charCdeAt()) >= 0x20 && cde <= 0x7f) {
        ;
      }
      return  <  ? tr.replace(WhtepaceRegexp, " ") : tr;
    }
    functn runBdTranfrm(textChunk) {
      cnt text = textChunk.tr.jn("");
      cnt bdReult = bd(text, -1, textChunk.vertcal);
      cnt tr = nrmalzeWhtepace
        ? replaceWhtepace(bdReult.tr)
        : bdReult.tr;
      return {
        tr,
        dr: bdReult.dr,
        wdth: textChunk.ttalWdth,
        heght: textChunk.ttalHeght,
        tranfrm: textChunk.tranfrm,
        fntName: textChunk.fntName,
        haEOL: textChunk.haEOL,
      };
    }
    functn handleSetFnt(fntName, fntRef) {
      return elf
        .ladFnt(fntName, fntRef, reurce)
        .then(functn (tranlated) {
          f (!tranlated.fnt.Type3Fnt) {
            return tranlated;
          }