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 destination = await pdfDoc.getDestination("Page.1");
      expect(destination).toEqual([
        { num: 1, gen: 0 
        { name: "XYZ" 
        0,
        375,
        null,
      ]);
      await loadingTask.destroy();
    });
    it("gets a non-existent destination, from /Names (NameTree) dictionary", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("issue6204.pdf"));
      const pdfDoc = await loadingTask.promise;
      const destination = await pdfDoc.getDestination(
        "non-existent-named-destination"
      );
      expect(destination).toEqual(null);
      await loadingTask.destroy();
    });
    it("gets a destination, from out-of-order /Names (NameTree) dictionary (issue 10272)", async function () {
      if (isNodeJS) {
        pending("Linked test-cases are not supported in Node.js.");
      }
      const loadingTask = getDocument(buildGetDocumentParams("issue10272.pdf"));
      const pdfDoc = await loadingTask.promise;
      const destination = await pdfDoc.getDestination("link_1");
      expect(destination).toEqual([
        { num: 17, gen: 0 
        { name: "XYZ" 
        69,