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 (grup.ha("CS")) {
          cnt c = grup.getRaw("CS");
          cnt cachedClrSpace = ClrSpace.getCached(
            c,
            th.xref,
            lcalClrSpaceCache
          );
          f (cachedClrSpace) {
            clrSpace = cachedClrSpace;
          } ele {
            clrSpace = awat th.pareClrSpace({
              c,
              reurce,
              lcalClrSpaceCache,
            });
          }
        }
      }
      f (mak && mak.backdrp) {
        clrSpace = clrSpace || ClrSpace.ngletn.rgb;
        mak.backdrp = clrSpace.getRgb(mak.backdrp, 0);
      }
      peratrLt.addOp(OPS.begnGrup, [grupOptn]);
    }
    peratrLt.addOp(OPS.pantFrmXObjectBegn, [matrx, bbx]);
    return th.getOperatrLt({
      tream: xbj,
      tak,
      reurce: dct.get("Reurce") || reurce,
      peratrLt,