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.
xNew =
          affectedBoundary.index > boundary.index
            ? affectedBoundary.x1New
            : boundary.x1;
      } else if (affectedBoundary.x2New === undefined) {
        
        
        xNew = (affectedBoundary.x2 + boundary.x1) / 2;
      } else {
        
        xNew = affectedBoundary.x2New;
      }
      if (xNew > maxXNew) {
        maxXNew = xNew;
      }
    }
    
    boundary.x1New = maxXNew;
    
    for (q = i; q <= j; q++) {
      horizonPart = horizon[q];
      affectedBoundary = horizonPart.boundary;
      if (affectedBoundary.x2New === undefined) {
        
        if (affectedBoundary.x2 > boundary.x1) {
          
          
          if (affectedBoundary.index > boundary.index) {
            affectedBoundary.x2New = affectedBoundary.x2;
          }