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.
const bounds = task._bounds;
  const viewport = task._viewport;
  const expanded = expandBounds(viewport.width, viewport.height, bounds);
  for (let i = 0; i < expanded.length; i++) {
    const div = bounds[i].div;
    const divProperties = task._textDivProperties.get(div);
    if (divProperties.angle === 0) {
      divProperties.paddingLeft = bounds[i].left - expanded[i].left;
      divProperties.paddingTop = bounds[i].top - expanded[i].top;
      divProperties.paddingRight = expanded[i].right - bounds[i].right;
      divProperties.paddingBottom = expanded[i].bottom - bounds[i].bottom;
      task._textDivProperties.set(div, divProperties);
      continue;
    }
    
    
    const e = expanded[i],
      b = bounds[i];
    const m = b.m,
      c = m[0],
      s = m[1];
    
    const points = [[0, 0], [0, b.size[1]], [b.size[0], 0], b.size];
    const ts = new Float64Array(64);