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 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;
  }