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.
) {
          passwordNeededCapability.resolve();
          updatePassword("qwerty"); 
          return;
        }
        if (
          reason === PasswordResponses.INCORRECT_PASSWORD &&
          !passwordIncorrectCapability.settled
        ) {
          passwordIncorrectCapability.resolve();
          updatePassword("asdfasdf"); 
          return;
        }
        
        expect(false).toEqual(true);
      };
      const data = await Promise.all([
        passwordNeededCapability.promise,
        passwordIncorrectCapability.promise,
        loadingTask.promise,
      ]);
      expect(data[2] instanceof PDFDocumentProxy).toEqual(true);
      await loadingTask.destroy();
    });
    it("creates pdf doc from PDF file protected with only a user password", async function () {
      const filename = "pr6531_2.pdf";
      const passwordNeededLoadingTask = getDocument(
        buildGetDocumentParams(filename, {
          password: "",
        })