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.
expect(loadingTask).toEqual(data[1].loadingTask);
      await loadingTask.destroy();
    });
    it("creates pdf doc from URL and aborts before worker initialized", async function () {
      const loadingTask = getDocument(basicApiGetDocumentParams);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      const destroyed = loadingTask.destroy();
      try {
        await loadingTask.promise;
        
        expect(false).toEqual(true);
      } catch (reason) {
        expect(true).toEqual(true);
        await destroyed;
      }
    });
    it("creates pdf doc from URL and aborts loading after worker initialized", async function () {
      const loadingTask = getDocument(basicApiGetDocumentParams);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      
      
      const destroyed = loadingTask._worker.promise.then(function () {
        return loadingTask.destroy();
      });
      await destroyed;
      expect(true).toEqual(true);
    });
    it("creates pdf doc from typed array", async function () {
      const typedArrayPdf = await DefaultFileReaderFactory.fetch({
        path: TEST_PDFS_PATH + basicApiFileName,