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.
used = horizon[k].boundary === affectedBoundary;
      }
      for (
        k = j + 1;
        !used && k < horizon.length && horizon[k].end <= affectedBoundary.y2;
        k++
      ) {
        used = horizon[k].boundary === affectedBoundary;
      }
      for (k = 0; !used && k < changedHorizon.length; k++) {
        used = changedHorizon[k].boundary === affectedBoundary;
      }
      if (!used) {
        affectedBoundary.x2New = maxXNew;
      }
    }
    Array.prototype.splice.apply(
      horizon,
      [i, j - i + 1].concat(changedHorizon)
    );
  }
  
  for (const horizonPart of horizon) {
    const affectedBoundary = horizonPart.boundary;
    if (affectedBoundary.x2New === undefined) {
      affectedBoundary.x2New = Math.max(width, affectedBoundary.x2);
    }
  }
}
class TextLayerRenderTask {