Attach (recommended) or Link to PDF file here:

Configuration:
- Web browser and its version: Version 81.0.4044.138 (Official Build) (32-bit)
- Operating system and its version: Windows 10
- PDF.js version: latest
- Is a browser extension: no

Steps to reproduce the problem:

1. Open https://mozilla.github.io/pdf.js/web/viewer.html
2. Open the provided document
3. ctrl + F  and search for 'costs' .
4. Search for 'costs' - match NOT found.
5. Click the 'Download' and open the file in Adobe Reader, and search for costs - match is found.

What is the expected behavior? (add screenshot)
The word 'costs' to be returned by search

What went wrong? (add screenshot)
No results found

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):  https://mozilla.github.io/pdf.js/web/viewer.html
[2001_IESC_63_5_v6.pdf](https://github.com/mozilla/pdf.js/files/4644486/2001_IESC_63_5_v6.pdf)

expect(outline).toEqual(null);
      await loadingTask.destroy();
    });
    it("gets outline", async function () {
      const outline = await pdfDocument.getOutline();
      
      expect(Array.isArray(outline)).toEqual(true);
      expect(outline.length).toEqual(2);
      
      const outlineItem = outline[1];
      expect(outlineItem.title).toEqual("Chapter 1");
      expect(Array.isArray(outlineItem.dest)).toEqual(true);
      expect(outlineItem.url).toEqual(null);
      expect(outlineItem.unsafeUrl).toBeUndefined();
      expect(outlineItem.newWindow).toBeUndefined();
      expect(outlineItem.bold).toEqual(true);
      expect(outlineItem.italic).toEqual(false);
      expect(outlineItem.color).toEqual(new Uint8ClampedArray([0, 64, 128]));
      expect(outlineItem.items.length).toEqual(1);
      expect(outlineItem.items[0].title).toEqual("Paragraph 1.1");
    });
    it("gets outline containing a URL", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("issue3214.pdf"));
      const pdfDoc = await loadingTask.promise;
      const outline = await pdfDoc.getOutline();
      expect(Array.isArray(outline)).toEqual(true);
      expect(outline.length).toEqual(5);
      const outlineItemTwo = outline[2];
      expect(typeof outlineItemTwo.title).toEqual("string");
      expect(outlineItemTwo.dest).toEqual(null);