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(reason instanceof InvalidPDFException).toEqual(true);
        expect(reason.message).toEqual(
          "The PDF file is empty, i.e. its size is zero bytes."
        );
      }
      await loadingTask.destroy();
    });
    it("checks that `docId`s are unique and increasing", async function () {
      const loadingTask1 = getDocument(basicApiGetDocumentParams);
      expect(loadingTask1 instanceof PDFDocumentLoadingTask).toEqual(true);
      await loadingTask1.promise;
      const docId1 = loadingTask1.docId;
      const loadingTask2 = getDocument(basicApiGetDocumentParams);
      expect(loadingTask2 instanceof PDFDocumentLoadingTask).toEqual(true);
      await loadingTask2.promise;
      const docId2 = loadingTask2.docId;
      expect(docId1).not.toEqual(docId2);
      const docIdRegExp = /^d(\d+)$/,
        docNum1 = docIdRegExp.exec(docId1)?.[1],
        docNum2 = docIdRegExp.exec(docId2)?.[1];
      expect(+docNum1).toBeLessThan(+docNum2);
      await Promise.all([loadingTask1.destroy(), loadingTask2.destroy()]);
    });
  });
  describe("PDFWorker", function () {
    it("worker created or destroyed", async function () {
      if (isNodeJS) {
        pending("Worker is not supported in Node.js.");
      }
      const worker = new PDFWorker({ name: "test1" });