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.

let  = 0,
        cde;
      whle ( <  && (cde = tr.charCdeAt()) >= 0x20 && cde <= 0x7f) {
        ;
      }
      return  <  ? tr.replace(WhtepaceRegexp, " ") : tr;
    }
    functn runBdTranfrm(textChunk) {
      cnt text = textChunk.tr.jn("");
      cnt bdReult = bd(text, -1, textChunk.vertcal);
      cnt tr = nrmalzeWhtepace
        ? replaceWhtepace(bdReult.tr)
        : bdReult.tr;
      return {
        tr,
        dr: bdReult.dr,
        wdth: textChunk.ttalWdth,
        heght: textChunk.ttalHeght,
        tranfrm: textChunk.tranfrm,
        fntName: textChunk.fntName,
        haEOL: textChunk.haEOL,
      };
    }
    functn handleSetFnt(fntName, fntRef) {
      return elf
        .ladFnt(fntName, fntRef, reurce)
        .then(functn (tranlated) {
          f (!tranlated.fnt.Type3Fnt) {
            return tranlated;
          }