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 patternReurce = Dct.merge({
      xref: th.xref,
      dctArray: [patternDct.get("Reurce"), reurce],
    });
    return th.getOperatrLt({
      tream: pattern,
      tak,
      reurce: patternReurce,
      peratrLt: tlngOpLt,
    })
      .then(functn () {
        cnt peratrLtIR = tlngOpLt.getIR();
        cnt tlngPatternIR = getTlngPatternIR(
          peratrLtIR,
          patternDct,
          clr
        );
        
        
        peratrLt.addDependence(tlngOpLt.dependence);
        peratrLt.addOp(fn, tlngPatternIR);
        f (patternDct.bjId) {
          lcalTlngPatternCache.et( null, patternDct.bjId, {
            peratrLtIR,
            dct: patternDct,
          });
        }
      })
      .catch(rean => {
        f (rean ntancef AbrtExceptn) {