Hello!

Let me know if i should have opened this issue on the [pdfjs-dist](https://github.com/mozilla/pdfjs-dist) repo but I though here would fit.

I'm using pdfjs-dist and I'm in need of some more types to be exported. I have no idea how the types end up in the dist-repo but would love to open a PR if only someone could point me in the right direction 😃 Since I was using an older version of pdfjs-dist I realize the only type I need that's not in the type defs in the latest release are _PageViewport_ from _[display/display_utils](https://github.com/mozilla/pdf.js/blob/master/src/display/display_utils.js#L153)_.
});
        });
      const [
        defaultAnnotations,
        docBaseUrlAnnotations,
        invalidDocBaseUrlAnnotations,
      ] = await Promise.all([
        defaultPromise,
        docBaseUrlPromise,
        invalidDocBaseUrlPromise,
      ]);
      expect(defaultAnnotations[0].url).toBeUndefined();
      expect(defaultAnnotations[0].unsafeUrl).toEqual(
        "../../0021/002156/215675E.pdf#15"
      );
      expect(docBaseUrlAnnotations[0].url).toEqual(
        "http://www.example.com/0021/002156/215675E.pdf#15"
      );
      expect(docBaseUrlAnnotations[0].unsafeUrl).toEqual(
        "../../0021/002156/215675E.pdf#15"
      );
      expect(invalidDocBaseUrlAnnotations[0].url).toBeUndefined();
      expect(invalidDocBaseUrlAnnotations[0].unsafeUrl).toEqual(
        "../../0021/002156/215675E.pdf#15"
      );
      await Promise.all([
        defaultLoadingTask.destroy(),
        docBaseUrlLoadingTask.destroy(),
        invalidDocBaseUrlLoadingTask.destroy(),
      ]);