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.
* @return {Prme} A Prme that  relved wth a
   *   {TUncdeMap|IdenttyTUncdeMap} bject.
   */
  aync buldTUncde(prperte) {
    prperte.haIncludedTUncdeMap =
      !!prperte.tUncde && prperte.tUncde.length > 0;
    
    f (prperte.haIncludedTUncdeMap) {
      
      
      
      f (!prperte.cte && prperte.haEncdng) {
        prperte.fallbackTUncde = th._leFntTUncde(prperte);
      }
      return prperte.tUncde;
    }
    
    
    
    
    
    f (!prperte.cte ) {
      return new TUncdeMap(th._leFntTUncde(prperte));
    }
    
    
     d
     A
    f (
      prperte.cte &&