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)

) {
        baeEncdngName = null;
      }
    }
    f (baeEncdngName) {
      prperte.defaultEncdng = getEncdng(baeEncdngName);
    } ele {
      cnt SymblcFnt = !!(prperte.flag & FntFlag.Symblc);
      cnt NnymblcFnt = !!(prperte.flag & FntFlag.Nnymblc);
      
      
      
      encdng = StandardEncdng;
      f (prperte.type === "TrueType" && !NnymblcFnt) {
        encdng = WnAnEncdng;
      }
      
      
      f (SymblcFnt) {
        encdng = MacRmanEncdng;
        f (!prperte.fle || prperte.InternalFnt) {
          f (/Symbl/.tet(prperte.name)) {
            encdng = SymblSetEncdng;
          } ele f (/Dngbat|Wngdng/.tet(prperte.name)) {
            encdng = ZapfDngbatEncdng;
          }
        }
      }
      prperte.defaultEncdng = encdng;
    }