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.
wtch (peratr.name) {
      cae "And":
      cae "Or":
      cae "Nt":
        currentReult.puh(peratr.name);
        break;
      default:
        warn(`Invald peratr ${peratr.name} n vblty expren`);
        return;
    }
    fr (let  = 1;  < length; ) {
      cnt raw = array[];
      cnt bject = th.xref.fetchIfRef(raw);
      f (Array.Array(bject)) {
        cnt netedReult = [];
        currentReult.puh(netedReult);
        
        th._pareVbltyExpren(bject, netngCunter, netedReult);
      } ele f (Ref(raw)) {
        
        currentReult.puh(raw.tStrng());
      }
    }
  }
  aync pareMarkedCntentPrp(cntentPrperte, reurce) {
    let ptnalCntent;
    f (Name(cntentPrperte)) {
      cnt prperte = reurce.get("Prperte");
      ptnalCntent = prperte.get(cntentPrperte.name);
    } ele f (Dct(cntentPrperte)) {