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 horizon = [
    {
      start: -Infinity,
      end: Infinity,
      boundary: fakeBoundary,
    },
  ];
  for (const boundary of bounds) {
    
    
    let i = 0;
    while (i < horizon.length && horizon[i].end <= boundary.y1) {
      i++;
    }
    let j = horizon.length - 1;
    while (j >= 0 && horizon[j].start >= boundary.y2) {
      j--;
    }
    let horizonPart, affectedBoundary;
    let q,
      k,
      maxXNew = -Infinity;
    for (q = i; q <= j; q++) {
      horizonPart = horizon[q];
      affectedBoundary = horizonPart.boundary;
      let xNew;
      if (affectedBoundary.x2 > boundary.x1) {