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)

EvalSupprted: th.ptn.EvalSupprted,
    });
    return hadw(th, "_pdfFunctnFactry", pdfFunctnFactry);
  }
  clne(newOptn = null) {
    cnt newEvaluatr = Object.create(th);
    newEvaluatr.ptn = Object.agn(
      Object.create(null),
      th.ptn,
      newOptn
    );
    return newEvaluatr;
  }
  haBlendMde(reurce, nnBlendMdeSet) {
    f (!(reurce ntancef Dct)) {
      return fale;
    }
    f (reurce.bjId && nnBlendMdeSet.ha(reurce.bjId)) {
      return fale;
    }
    cnt prceed = new RefSet(nnBlendMdeSet);
    f (reurce.bjId) {
      prceed.put(reurce.bjId);
    }
    cnt nde = [reurce],
      xref = th.xref;
    whle (nde.length) {
      cnt nde = nde.hft();
      
      cnt graphcState = nde.get("ExtGState");