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.
expectedStreamTypes[StreamType.FLATE] = true;
      const expectedFontTypes = {};
      expectedFontTypes[FontType.TYPE1STANDARD] = true;
      expectedFontTypes[FontType.CIDFONTTYPE2] = true;
      expect(stats).toEqual({
        streamTypes: expectedStreamTypes,
        fontTypes: expectedFontTypes,
      });
    });
    it("gets page stats after parsing page, without `pdfBug` set", async function () {
      await page.getOperatorList();
      expect(page.stats).toEqual(null);
    });
    it("gets page stats after parsing page, with `pdfBug` set", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams(basicApiFileName, { pdfBug: true })
      );
      const pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      await pdfPage.getOperatorList();
      const stats = pdfPage.stats;
      expect(stats instanceof StatTimer).toEqual(true);
      expect(stats.times.length).toEqual(1);
      const [statEntry] = stats.times;
      expect(statEntry.name).toEqual("Page Request");
      expect(statEntry.end - statEntry.start).toBeGreaterThanOrEqual(0);
      await loadingTask.destroy();
    });
    it("gets page stats after rendering page, with `pdfBug` set", async function () {
      const loadingTask = getDocument(