Attach (recommended) or Link to PDF file here:
https://bitcoin.org/bitcoin.pdf

Configuration:
- Web browser and its version: all
- Operating system and its version: all
- PDF.js version: tested with 2.9.11, but most likely all versions
- Is a browser extension: no

Steps to reproduce the problem:
1. Type "a purely" (single space between "a" and "purely") - doesn't find anything
2. Type "a  purely" (two spaces between "a" and "purely") - finds the phrase

Sometimes even 3 spaces are necessary.

What is the expected behavior? (add screenshot)
![Screenshot from 2021-04-08 13-00-03](https://user-images.githubusercontent.com/6362989/114008903-57639a00-986b-11eb-903a-92bbebbd922b.png)

What went wrong? (add screenshot)
![Screenshot from 2021-04-08 13-01-53](https://user-images.githubusercontent.com/6362989/114008810-44e96080-986b-11eb-8232-f58a62ed7899.png)

This affects many PDFs because justify alignment is common enough.
b.y1 = width - e.right;
    b.x2 = box.bottom;
    b.y2 = width - e.left;
    b.index = i;
    b.x1New = undefined;
    b.x2New = undefined;
  });
  expandBoundsLTR(height, bounds);
  for (const b of bounds) {
    const i = b.index;
    expanded[i].top = b.x1New;
    expanded[i].bottom = b.x2New;
  }
  return expanded;
}
function expandBoundsLTR(width, bounds) {
  
  bounds.sort(function (a, b) {
    return a.x1 - b.x1 || a.index - b.index;
  });
  
  const fakeBoundary = {
    x1: -Infinity,
    y1: -Infinity,
    x2: 0,
    y2: Infinity,
    index: -1,
    x1New: 0,
    x2New: 0,
  };