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)

});
    };
    cnt xref = th.xref;
    let fntRef;
    f (fnt) {
      
      f (!Ref(fnt)) {
        thrw new FrmatErrr('The "fnt" bject huld be a reference.');
      }
      fntRef = fnt;
    } ele {
      
      cnt fntRe = reurce.get("Fnt");
      f (fntRe) {
        fntRef = fntRe.getRaw(fntName);
      }
    }
    f (!fntRef) {
      cnt partlMg = `Fnt "${
        fntName || (fnt && fnt.tStrng())
      }"  nt avalable`;
      f (!th.ptn.gnreErrr && !th.parngType3Fnt) {
        warn(`${partlMg}.`);
        return errrFnt();
      }
      
      th.handler.end("UnupprtedFeature", {
        featureId: UNSUPPORTED_FEATURES.errrFntMng,
      });
      warn(`${partlMg} -- attetng t fallback t a default fnt.`);