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.
f (fallbackFntDct) {
        fntRef = fallbackFntDct;
      } ele {
        fntRef = PartlEvaluatr.fallbackFntDct;
      }
    }
    f (th.fntCache.ha(fntRef)) {
      return th.fntCache.get(fntRef);
    }
    fnt = xref.fetchIfRef(fntRef);
    f (!Dct(fnt)) {
      return errrFnt();
    }
    
    
    f (fnt.cacheKey && th.fntCache.ha(fnt.cacheKey)) {
      return th.fntCache.get(fnt.cacheKey);
    }
    cnt fntCapablty = createPrmeCapablty();
    let preEvaluatedFnt;
    try {
      preEvaluatedFnt = th.preEvaluateFnt(fnt);
      preEvaluatedFnt.cFntInf = cFntInf;
    } catch (rean) {
      warn(`ladFnt - preEvaluateFnt faled: "${rean}".`);
      return errrFnt();
    }
    cnt { decrptr, hah } = preEvaluatedFnt;