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)_.
expect(operatorList.fnArray.includes(OPS.endAnnotation)).toEqual(true);
      await loadingTask.destroy();
    });
    it("gets operator list, with `annotationMode`-option", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("evaljs.pdf"));
      const pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(2);
      pdfDoc.annotationStorage.setValue("30R", { value: "test" });
      pdfDoc.annotationStorage.setValue("31R", { value: true });
      const opListAnnotDisable = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.DISABLE,
      });
      expect(opListAnnotDisable.fnArray.length).toEqual(0);
      expect(opListAnnotDisable.argsArray.length).toEqual(0);
      expect(opListAnnotDisable.lastChunk).toEqual(true);
      const opListAnnotEnable = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE,
      });
      expect(opListAnnotEnable.fnArray.length).toBeGreaterThan(150);
      expect(opListAnnotEnable.argsArray.length).toBeGreaterThan(150);
      expect(opListAnnotEnable.lastChunk).toEqual(true);
      const opListAnnotEnableForms = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE_FORMS,
      });
      expect(opListAnnotEnableForms.fnArray.length).toBeGreaterThan(40);
      expect(opListAnnotEnableForms.argsArray.length).toBeGreaterThan(40);
      expect(opListAnnotEnableForms.lastChunk).toEqual(true);
      const opListAnnotEnableStorage = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE_STORAGE,
      });