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.
const data = await Promise.all([
        loadingTask1.promise,
        loadingTask2.promise,
      ]);
      const fingerprints1 = data[0].fingerprints;
      const fingerprints2 = data[1].fingerprints;
      expect(fingerprints1).not.toEqual(fingerprints2);
      expect(fingerprints1).toEqual(["2f695a83d6e7553c24fc08b7ac69712d", null]);
      expect(fingerprints2).toEqual(["04c7126b34a46b6d4d6e7a1eff7edcb6", null]);
      await Promise.all([loadingTask1.destroy(), loadingTask2.destroy()]);
    });
    it("write a value in an annotation, save the pdf and load it", async function () {
      let loadingTask = getDocument(buildGetDocumentParams("evaljs.pdf"));
      let pdfDoc = await loadingTask.promise;
      const value = "Hello World";
      pdfDoc.annotationStorage.setValue("55R", { value });
      const data = await pdfDoc.saveDocument();
      await loadingTask.destroy();
      loadingTask = getDocument(data);
      pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      const annotations = await pdfPage.getAnnotations();
      const field = annotations.find(annotation => annotation.id === "55R");
      expect(!!field).toEqual(true);
      expect(field.fieldValue).toEqual(value);
      await loadingTask.destroy();
    });
    describe("Cross-origin", function () {
      let loadingTask;
      function _checkCanLoad(expectSuccess, filename, options) {