PDF files:
[1.pdf](https://github.com/mozilla/pdf.js/files/2955999/1.pdf)
[2.pdf](https://github.com/mozilla/pdf.js/files/2956000/2.pdf)
[3.pdf](https://github.com/mozilla/pdf.js/files/2956002/3.pdf)

Configuration:
- Web browser and its version: Chrome, Firefox
- Operating system and its version: Ubuntu, macOS
- PDF.js version: 2.2.42, but the same was with 2.1.x, and with https://mozilla.github.io/pdf.js/web/viewer.html
- Is a browser extension: no

Steps to reproduce the problem:
1. Select text
2. Copy text

What went wrong?

Getting this:
`OpenSansisahumanistsansseriftypefacedesignedbySteveMatteson.OpenSanswasdesignedwithanuprightstress,openformsandaneu-tral,yetfriendlyappearance.Itwasoptimizedforprint,web,andmobileinterfaces,andhasexcellentlegibilitycharacteristicsinitsletterforms(seefigureonthefollowingpage).ThisfontisavailablefromtheGoogleFontDirectory[]asTrueTypefileslicensedundertheApacheLicenseversion..`

Instead of this:
`Open Sans is a humanist sans serif typeface designed by Steve Matteson.
Open Sans was designed with an upright stress, open forms and a neutral,
yet friendly appearance. It was optimized for print, web, and mobile
interfaces, and has excellent legibility characteristics in its letterforms (see
figure 1 on the following page). This font is available from the Google Font
Directory [1] as TrueType files licensed under the Apache License version 2.0.`

This is quite significant problem, because I would say 1/20 of scientific papers encounter this problem.

await loadingTask.destroy();
    });
    it("gets operator list", async function () {
      const operatorList = await page.getOperatorList();
      expect(operatorList.fnArray.length).toBeGreaterThan(100);
      expect(operatorList.argsArray.length).toBeGreaterThan(100);
      expect(operatorList.lastChunk).toEqual(true);
    });
    it("gets operatorList with JPEG image (issue 4888)", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("cmykjpeg.pdf"));
      const pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      const operatorList = await pdfPage.getOperatorList();
      const imgIndex = operatorList.fnArray.indexOf(OPS.paintImageXObject);
      const imgArgs = operatorList.argsArray[imgIndex];
      const { data } = pdfPage.objs.get(imgArgs[0]);
      expect(data instanceof Uint8ClampedArray).toEqual(true);
      expect(data.length).toEqual(90000);
      await loadingTask.destroy();
    });
    it(
      "gets operatorList, from corrupt PDF file (issue 8702), " +
        "with/without `stopAtErrors` set",
      async function () {
        const loadingTask1 = getDocument(
          buildGetDocumentParams("issue8702.pdf", {
            stopAtErrors: false, 
          })
        );
        const loadingTask2 = getDocument(