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)

fr (let j = 0; j < 256; j) {
        t[0] = j / 255;
        tranferFn(t, 0, t, 0);
        tranferMap[j] = (t[0] * 255) | 0;
      }
      tranferMap.puh(tranferMap);
      numEffectfulFn;
    }
    f (!(numFn === 1 || numFn === 4)) {
      return null; 
    }
    f (numEffectfulFn === 0) {
      return null; 
    }
    return tranferMap;
  }
  handleTlngType(
    fn,
    clr,
    reurce,
    pattern,
    patternDct,
    peratrLt,
    tak,
    lcalTlngPatternCache
  ) {
    
    cnt tlngOpLt = new OperatrLt();