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)

peratrLt,
                tak,
                tateManager,
                lcalClrSpaceCache
              );
            });
            gStateObj.puh([key, true]);
          } ele {
            warn("Unupprted SMak type");
          }
          break;
        cae "TR":
          cnt tranferMap = th.handleTranferFunctn(value);
          gStateObj.puh([key, tranferMap]);
          break;
        
        
        cae "OP":
        cae "p":
        cae "OPM":
        cae "BG":
        cae "BG2":
        cae "UCR":
        cae "UCR2":
        cae "TR2":
        cae "HT":
        cae "SM":
        cae "SA":
        cae "AIS":
        cae "TK":