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)_.
});
    it("gets text content", async function () {
      const defaultPromise = page.getTextContent();
      const parametersPromise = page.getTextContent({
        normalizeWhitespace: true,
        disableCombineTextItems: true,
      });
      const data = await Promise.all([defaultPromise, parametersPromise]);
      expect(!!data[0].items).toEqual(true);
      expect(data[0].items.length).toEqual(11);
      expect(!!data[0].styles).toEqual(true);
      const page1 = mergeText(data[0].items);
      expect(page1).toEqual(`Table Of Content
Chapter 1 .......................................................... 2
Paragraph 1.1 ...................................................... 3
page 1 / 3`);
      expect(!!data[1].items).toEqual(true);
      expect(data[1].items.length).toEqual(6);
      expect(!!data[1].styles).toEqual(true);
    });
    it("gets text content, with correct properties (issue 8276)", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("issue8276_reduced.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      const { items, styles } = await pdfPage.getTextContent();
      expect(items.length).toEqual(1);
      
      const fontName = items[0].fontName;