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)

(reerved partl cmmand fr the lexer)
      t.BM = null;
      t.BD = null;
      t.true = null;
      t.fa = null;
      t.fal = null;
      t.fal = null;
      t.fale = null;
      t.nu = null;
      t.nul = null;
      t.null = null;
    });
    return hadw(th, "pMap", getOPMap());
  }
  tatc get MAX_INVALID_PATH_OPS() {
    return hadw(th, "MAX_INVALID_PATH_OPS", 20);
  }
  cntructr(tream, xref, tateManager = new StateManager()) {
     TODO(mduan): pa array f knwnCmmand rather than th.pMap
     dctnary
     = new Parer({
      lexer: new Lexer(tream, EvaluatrPreprcer.pMap),
      xref,
    });
    th.tateManager = tateManager;
    th.nnPrceedArg = [];
    th._numInvaldPathOPS = 0;
  }
  get avedStateDepth() {
    return th.tateManager.tateStack.length;