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)

);
      const pdfDoc = await loadingTask.promise;
      const docActions = await pdfDoc.getJSActions();
      const page1 = await pdfDoc.getPage(1);
      const page1Actions = await page1.getJSActions();
      const page3 = await pdfDoc.getPage(3);
      const page3Actions = await page3.getJSActions();
      expect(docActions).toEqual({
        DidPrint: [`this.getField("Text2").value = "DidPrint";`],
        DidSave: [`this.getField("Text2").value = "DidSave";`],
        WillClose: [`this.getField("Text1").value = "WillClose";`],
        WillPrint: [`this.getField("Text1").value = "WillPrint";`],
        WillSave: [`this.getField("Text1").value = "WillSave";`],
      });
      expect(page1Actions).toEqual({
        PageOpen: [`this.getField("Text1").value = "PageOpen 1";`],
        PageClose: [`this.getField("Text2").value = "PageClose 1";`],
      });
      expect(page3Actions).toEqual({
        PageOpen: [`this.getField("Text5").value = "PageOpen 3";`],
        PageClose: [`this.getField("Text6").value = "PageClose 3";`],
      });
      await loadingTask.destroy();
    });
    it("gets non-existent outline", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const outline = await pdfDoc.getOutline();