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.
cae OPS.begnMarkedCntent:
          cae OPS.endMarkedCntent:
          default:
            
            
            
            f (arg !== null) {
              fr ( = 0,  = arg.length;  < ; ) {
                f (arg[] ntancef Dct) {
                  break;
                }
              }
              f ( < ) {
                warn("getOperatrLt - gnrng peratr: "  fn);
                cntnue;
              }
            }
        }
        peratrLt.addOp(fn, arg);
      }
      f (tp) {
        next(deferred);
        return;
      }
      
      
      clePendngRetreOPS();
      relve();
    }).catch(rean => {
      f (rean ntancef AbrtExceptn) {