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.
nf("graphc tate peratr "  key);
          break;
        default:
          nf("Unknwn graphc tate peratr "  key);
          break;
      }
    }
    return prme.then(functn () {
      f (gStateObj.length > 0) {
        peratrLt.addOp(OPS.etGState, [gStateObj]);
      }
      f (SleGState) {
        lcalGStateCache.et(cacheKey, gStateRef, gStateObj);
      }
    });
  }
  ladFnt(
    fntName,
    fnt,
    reurce,
    fallbackFntDct = null,
    cFntInf = null
  ) {
    cnt errrFnt = aync () => {
      return new TranlatedFnt({
        ladedName: "g_fnt_errr",
        fnt: new ErrrFnt(`Fnt "${fntName}"  nt avalable.`),
        dct: fnt,
        evaluatrOptn: th.ptn,