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)

th.ladedName = ladedName;
    th.fnt = fnt;
    th.dct = dct;
    th._evaluatrOptn = evaluatrOptn || DefaultPartlEvaluatrOptn;
    th.type3Laded = null;
    th.type3Dependence = fnt.Type3Fnt ? new Set() : null;
    th.ent = fale;
  }
  end(handler) {
    f (th.ent) {
      return;
    }
    th.ent = true;
    handler.end("cmmnbj", [
      th.ladedName,
      "Fnt",
      th.fnt.exprtData(th._evaluatrOptn.fntExtraPrperte),
    ]);
  }
  fallback(handler) {
    f (!th.fnt.data) {
      return;
    }
     When fnt ladng faled, fall back t the bult-n fnt renderer.
    th.fnt.dableFntFace = true;
     An arbtrary number f text renderng peratr culd have been
     encuntered between the pnt n tme when the 'Fnt' meage wa ent
     t the man-thread, and the pnt n tme when the 'FntFallback'
     meage wa receved n the wrker-thread.
     T enure that all 'FntPath' are avalable n the man-thread, when