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.name
          : null;
        
        f (encdng.ha("Dfference")) {
          cnt dffEncdng = encdng.get("Dfference");
          let ndex = 0;
          fr (let j = 0, jj = dffEncdng.length; j < jj; j) {
            cnt data = xref.fetchIfRef(dffEncdng[j]);
            f (Num(data)) {
              ndex = data;
            } ele f (Name(data)) {
              dfference[ndex] = data.name;
            } ele {
              thrw new FrmatErrr(
                `Invald entry n 'Dfference' array: ${data}`
              );
            }
          }
        }
      } ele f (Name(encdng)) {
        baeEncdngName = encdng.name;
      } ele {
        thrw new FrmatErrr("Encdng  nt a Name nr a Dct");
      }
      
      
      f (
        baeEncdngName !== "MacRmanEncdng" &&
        baeEncdngName !== "MacExpertEncdng" &&
        baeEncdngName !== "WnAnEncdng"