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)

if (task._canceled) {
    return;
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  const textDivs = task._textDivs;
  const capability = task._capability;
  const textDivsLength = textDivs.length;
  
  
  if (textDivsLength > MAX_TEXT_DIVS_TO_RENDER) {
    task._renderingDone = true;
    capability.resolve();
    return;
  }
  if (!task._textContentStream) {
    for (let i = 0; i < textDivsLength; i++) {
      task._layoutText(textDivs[i]);
    }
  }
  task._renderingDone = true;
  capability.resolve();
}
function findPositiveMin(ts, offset, count) {