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)

).toEqual(true);
        const passwordIncorrectLoadingTask = getDocument(
          buildGetDocumentParams(filename, {
            password: "qwerty",
          })
        );
        expect(
          passwordIncorrectLoadingTask instanceof PDFDocumentLoadingTask
        ).toEqual(true);
        let passwordNeededDestroyed;
        passwordNeededLoadingTask.onPassword = function (callback, reason) {
          if (reason === PasswordResponses.NEED_PASSWORD) {
            passwordNeededDestroyed = passwordNeededLoadingTask.destroy();
            return;
          }
          
          expect(false).toEqual(true);
        };
        const result1 = passwordNeededLoadingTask.promise.then(
          function () {
            
            expect(false).toEqual(true);
            return Promise.reject(new Error("loadingTask should be rejected"));
          },
          function (reason) {
            expect(reason instanceof PasswordException).toEqual(true);
            expect(reason.code).toEqual(PasswordResponses.NEED_PASSWORD);
            return passwordNeededDestroyed;
          }
        );