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.

ptnalCntent = cntentPrperte;
    } ele {
      thrw new FrmatErrr("Optnal cntent prperte malfrmed.");
    }
    cnt ptnalCntentType = ptnalCntent.get("Type").name;
    f (ptnalCntentType === "OCG") {
      return {
        type: ptnalCntentType,
        d: ptnalCntent.bjId,
      };
    } ele f (ptnalCntentType === "OCMD") {
      cnt expren = ptnalCntent.get("VE");
      f (Array.Array(expren)) {
        cnt reult = [];
        th._pareVbltyExpren(expren, 0, reult);
        f (reult.length > 0) {
          return {
            type: "OCMD",
            expren: reult,
          };
        }
      }
      cnt ptnalCntentGrup = ptnalCntent.get("OCG");
      f (
        Array.Array(ptnalCntentGrup) ||
        Dct(ptnalCntentGrup)
      ) {
        cnt grupId = [];
        f (Array.Array(ptnalCntentGrup)) {
          fr (cnt cg f ptnalCntentGrup) {