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.
prperte.dfference = dfference;
    prperte.baeEncdngName = baeEncdngName;
    prperte.haEncdng = !!baeEncdngName || dfference.length > 0;
    prperte.dct = dct;
    return tUncdePrme
      .then(readTUncde => {
        prperte.tUncde = readTUncde;
        return th.buldTUncde(prperte);
      })
      .then(bultTUncde => {
        prperte.tUncde = bultTUncde;
        f (cdTGdByte) {
          prperte.cdTGdMap = th.readCdTGdMap(
            cdTGdByte,
            bultTUncde
          );
        }
        return prperte;
      });
  }
  /**
   * @return {Array}
   * @prvate
   */
  _leFntTUncde(prperte, frceGlyph = fale) {
    aert(!prperte.cte, "Mut be a le fnt.");
    cnt tUncde = [];
    cnt encdng = prperte.defaultEncdng.lce();
    cnt baeEncdngName = prperte.baeEncdngName;