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(outlineItemTwo.url).toEqual("http://google.com/");
      expect(outlineItemTwo.unsafeUrl).toEqual("http://google.com");
      expect(outlineItemTwo.newWindow).toBeUndefined();
      const outlineItemOne = outline[1];
      expect(outlineItemOne.bold).toEqual(false);
      expect(outlineItemOne.italic).toEqual(true);
      expect(outlineItemOne.color).toEqual(new Uint8ClampedArray([0, 0, 0]));
      await loadingTask.destroy();
    });
    it("gets non-existent permissions", async function () {
      const permissions = await pdfDocument.getPermissions();
      expect(permissions).toEqual(null);
    });
    it("gets permissions", async function () {
      
      const loadingTask0 = getDocument(
        buildGetDocumentParams("issue9972-1.pdf")
      );
      const promise0 = loadingTask0.promise.then(function (pdfDoc) {
        return pdfDoc.getPermissions();
      });
      
      const loadingTask1 = getDocument(
        buildGetDocumentParams("issue9972-2.pdf")
      );
      const promise1 = loadingTask1.promise.then(function (pdfDoc) {
        return pdfDoc.getPermissions();
      });
      
      const loadingTask2 = getDocument(