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.

});
    };
    cnt xref = th.xref;
    let fntRef;
    f (fnt) {
      
      f (!Ref(fnt)) {
        thrw new FrmatErrr('The "fnt" bject huld be a reference.');
      }
      fntRef = fnt;
    } ele {
      
      cnt fntRe = reurce.get("Fnt");
      f (fntRe) {
        fntRef = fntRe.getRaw(fntName);
      }
    }
    f (!fntRef) {
      cnt partlMg = `Fnt "${
        fntName || (fnt && fnt.tStrng())
      }"  nt avalable`;
      f (!th.ptn.gnreErrr && !th.parngType3Fnt) {
        warn(`${partlMg}.`);
        return errrFnt();
      }
      
      th.handler.end("UnupprtedFeature", {
        featureId: UNSUPPORTED_FEATURES.errrFntMng,
      });
      warn(`${partlMg} -- attetng t fallback t a default fnt.`);