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.
this._pdfDocument = pdfDocument;
  }
  get pagesCount() {
    return this._pdfDocument.numPages;
  }
  get page() {
    return this._page;
  }
  set page(value) {
    this._page = value;
  }
}
async function initPdfFindController(filename) {
  const loadingTask = getDocument(
    buildGetDocumentParams(filename || tracemonkeyFileName)
  );
  const pdfDocument = await loadingTask.promise;
  const eventBus = new EventBus();
  const linkService = new MockLinkService();
  linkService.setDocument(pdfDocument);
  const pdfFindController = new PDFFindController({
    linkService,
    eventBus,
  });
  pdfFindController.setDocument(pdfDocument); 
  return { eventBus, pdfFindController };
}
function testSearch({
  eventBus,
  pdfFindController,