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(viewport.transform).toEqual([1, 0, 0, -1, 100, 741.89]);
    });
    it('gets viewport respecting "dontFlip" argument', function () {
      const scale = 1,
        rotation = 0;
      const viewport = page.getViewport({ scale, rotation });
      const dontFlipViewport = page.getViewport({
        scale,
        rotation,
        dontFlip: true,
      });
      expect(dontFlipViewport).not.toEqual(viewport);
      expect(dontFlipViewport).toEqual(viewport.clone({ dontFlip: true }));
      expect(viewport.transform).toEqual([1, 0, 0, -1, 0, 841.89]);
      expect(dontFlipViewport.transform).toEqual([1, 0, -0, 1, 0, 0]);
    });
    it("gets viewport with invalid rotation", function () {
      expect(function () {
        page.getViewport({ scale: 1, rotation: 45 });
      }).toThrow(
        new Error(
          "PageViewport: Invalid rotation, must be a multiple of 90 degrees."
        )
      );
    });
    it("gets annotations", async function () {
      const defaultPromise = page.getAnnotations().then(function (data) {
        expect(data.length).toEqual(4);
      });
      const anyPromise = page