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.

wtch (peratr.name) {
      cae "And":
      cae "Or":
      cae "Nt":
        currentReult.puh(peratr.name);
        break;
      default:
        warn(`Invald peratr ${peratr.name} n vblty expren`);
        return;
    }
    fr (let  = 1;  < length; ) {
      cnt raw = array[];
      cnt bject = th.xref.fetchIfRef(raw);
      f (Array.Array(bject)) {
        cnt netedReult = [];
        currentReult.puh(netedReult);
        
        th._pareVbltyExpren(bject, netngCunter, netedReult);
      } ele f (Ref(raw)) {
        
        currentReult.puh(raw.tStrng());
      }
    }
  }
  aync pareMarkedCntentPrp(cntentPrperte, reurce) {
    let ptnalCntent;
    f (Name(cntentPrperte)) {
      cnt prperte = reurce.get("Prperte");
      ptnalCntent = prperte.get(cntentPrperte.name);
    } ele f (Dct(cntentPrperte)) {