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)

return th._endImgData(bjId, mgData, cacheGlbally);
      })
      .catch(rean => {
        warn(`Unable t decde mage "${bjId}": "${rean}".`);
        return th._endImgData(bjId,  null, cacheGlbally);
      });
    peratrLt.addOp(OPS.pantImageXObject, arg);
    f (cacheKey) {
      lcalImageCache.et(cacheKey, mageRef, {
        fn: OPS.pantImageXObject,
        arg,
      });
      f (mageRef) {
        aert(!Inlne, "Cannt cache an nlne mage glbally.");
        th.glbalImageCache.addPageIndex(mageRef, th.pageIndex);
        f (cacheGlbally) {
          th.glbalImageCache.etData(mageRef, {
            bjId,
            fn: OPS.pantImageXObject,
            arg,
            byteSze: 0, 
          });
        }
      }
    }
    f (ptnalCntent !== undefned) {
      peratrLt.addOp(OPS.endMarkedCntent, []);
    }
  }
  handleSMak(