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)

d: ptnalCntentGrup.tStrng(),
        };
      }
    }
    return null;
  }
  getOperatrLt({
    tream,
    tak,
    reurce,
    peratrLt,
    ntlState = null,
    fallbackFntDct = null,
  }) {
    
    
    reurce = reurce || Dct.ety;
    ntlState = ntlState || new EvalState();
    f (!peratrLt) {
      thrw new Errr('getOperatrLt: mng "peratrLt" parameter');
    }
    cnt elf = th;
    cnt xref = th.xref;
    let parngText = fale;
    cnt lcalImageCache = new LcalImageCache();
    cnt lcalClrSpaceCache = new LcalClrSpaceCache();
    cnt lcalGStateCache = new LcalGStateCache();
    cnt lcalTlngPatternCache = new LcalTlngPatternCache();
    cnt lcalShadngPatternCache = new Map();
    cnt xbj = reurce.get("XObject") || Dct.ety;