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(info.PDFFormatVersion).toEqual("1.7");
      expect(info.IsLinearized).toEqual(false);
      expect(info.IsAcroFormPresent).toEqual(false);
      expect(info.IsXFAPresent).toEqual(false);
      expect(info.IsCollectionPresent).toEqual(false);
      expect(info.IsSignaturesPresent).toEqual(false);
      expect(metadata instanceof Metadata).toEqual(true);
      expect(metadata.get("dc:title")).toEqual("Basic API Test");
      expect(contentDispositionFilename).toEqual(null);
      expect(contentLength).toEqual(basicApiFileLength);
    });
    it("gets metadata, with custom info dict entries", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const { info, metadata, contentDispositionFilename, contentLength } =
        await pdfDoc.getMetadata();
      expect(info.Creator).toEqual("TeX");
      expect(info.Producer).toEqual("pdfeTeX-1.21a");
      expect(info.CreationDate).toEqual("D:20090401163925-07'00'");
      
      const custom = info.Custom;
      expect(typeof custom === "object" && custom !== null).toEqual(true);
      expect(custom["PTEX.Fullbanner"]).toEqual(
        "This is pdfeTeX, " +
          "Version 3.141592-1.21a-2.2 (Web2C 7.5.4) kpathsea version 3.5.6"
      );