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)

const textDiv = document.createElement("span");
  const textDivProperties = task._enhanceTextSelection
    ? {
        angle: 0,
        canvasWidth: 0,
        hasText: geom.str !== "",
        hasEOL: geom.hasEOL,
        originalTransform: null,
        paddingBottom: 0,
        paddingLeft: 0,
        paddingRight: 0,
        paddingTop: 0,
        scale: 1,
      }
    : {
        angle: 0,
        canvasWidth: 0,
        hasText: geom.str !== "",
        hasEOL: geom.hasEOL,
      };
  task._textDivs.push(textDiv);
  const tx = Util.transform(task._viewport.transform, geom.transform);
  let angle = Math.atan2(tx[1], tx[0]);
  const style = styles[geom.fontName];
  if (style.vertical) {
    angle += Math.PI / 2;
  }