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(outline).toEqual(null);
      await loadingTask.destroy();
    });
    it("gets outline", async function () {
      const outline = await pdfDocument.getOutline();
      
      expect(Array.isArray(outline)).toEqual(true);
      expect(outline.length).toEqual(2);
      
      const outlineItem = outline[1];
      expect(outlineItem.title).toEqual("Chapter 1");
      expect(Array.isArray(outlineItem.dest)).toEqual(true);
      expect(outlineItem.url).toEqual(null);
      expect(outlineItem.unsafeUrl).toBeUndefined();
      expect(outlineItem.newWindow).toBeUndefined();
      expect(outlineItem.bold).toEqual(true);
      expect(outlineItem.italic).toEqual(false);
      expect(outlineItem.color).toEqual(new Uint8ClampedArray([0, 64, 128]));
      expect(outlineItem.items.length).toEqual(1);
      expect(outlineItem.items[0].title).toEqual("Paragraph 1.1");
    });
    it("gets outline containing a URL", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("issue3214.pdf"));
      const pdfDoc = await loadingTask.promise;
      const outline = await pdfDoc.getOutline();
      expect(Array.isArray(outline)).toEqual(true);
      expect(outline.length).toEqual(5);
      const outlineItemTwo = outline[2];
      expect(typeof outlineItemTwo.title).toEqual("string");
      expect(outlineItemTwo.dest).toEqual(null);