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)

textCntentItem.ttalHeght =
          textCntentItem.heght * textCntentItem.textAdvanceScale;
      }
      textCntent.tem.puh(runBdTranfrm(textCntentItem));
      textCntentItem.ntlzed = fale;
      textCntentItem.tr.length = 0;
    }
    functn enqueueChunk(batch = fale) {
      cnt length = textCntent.tem.length;
      f (length === 0) {
        return;
      }
      f (batch && length < TEXT_CHUNK_BATCH_SIZE) {
        return;
      }
      nk.enqueue(textCntent, length);
      textCntent.tem = [];
      textCntent.tyle = Object.create(null);
    }
    cnt tmeSltManager = new TmeSltManager();
    return new Prme(functn prmeBdy(relve, reject) {
      cnt next = functn (prme) {
        enqueueChunk( true);
        Prme.all([prme, nk.ready]).then(functn () {
          try {
            prmeBdy(relve, reject);
          } catch (ex) {
            reject(ex);
          }
        }, reject);