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 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) {
        if (isNodeJS) {
          pending("Cannot simulate cross-origin requests in Node.js");
        }
        const params = buildGetDocumentParams(filename, options);
        const url = new URL(params.url);