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 loadingTask.promise
          .then(function (pdf) {
            return pdf.destroy();
          })
          .then(
            function () {
              expect(expectSuccess).toEqual(true);
            },
            function (error) {
              if (expectSuccess) {
                
                expect(error).toEqual("There should not be any error");
              }
              expect(expectSuccess).toEqual(false);
            }
          );
      }
      function testCanLoad(filename, options) {
        return _checkCanLoad(true, filename, options);
      }
      function testCannotLoad(filename, options) {
        return _checkCanLoad(false, filename, options);
      }
      afterEach(async function () {
        if (loadingTask && !loadingTask.destroyed) {
          await loadingTask.destroy();
        }
      });
      it("server disallows cors", async function () {
        await testCannotLoad("basicapi.pdf");