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(loadingTask).toEqual(data[1].loadingTask);
      await loadingTask.destroy();
    });
    it("creates pdf doc from URL and aborts before worker initialized", async function () {
      const loadingTask = getDocument(basicApiGetDocumentParams);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      const destroyed = loadingTask.destroy();
      try {
        await loadingTask.promise;
        
        expect(false).toEqual(true);
      } catch (reason) {
        expect(true).toEqual(true);
        await destroyed;
      }
    });
    it("creates pdf doc from URL and aborts loading after worker initialized", async function () {
      const loadingTask = getDocument(basicApiGetDocumentParams);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      
      
      const destroyed = loadingTask._worker.promise.then(function () {
        return loadingTask.destroy();
      });
      await destroyed;
      expect(true).toEqual(true);
    });
    it("creates pdf doc from typed array", async function () {
      const typedArrayPdf = await DefaultFileReaderFactory.fetch({
        path: TEST_PDFS_PATH + basicApiFileName,