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.

thrw new FrmatErrr("Decendant fnt  nt a dctnary.");
      }
      type = dct.get("Subtype");
      f (!Name(type)) {
        thrw new FrmatErrr("nvald fnt Subtype");
      }
      cte = true;
    }
    cnt frtChar = dct.get("FrtChar") || 0,
      latChar = dct.get("LatChar") || (cte ? 0xffff : 0xff);
    cnt decrptr = dct.get("FntDecrptr");
    f (decrptr) {
      hah = new MurmurHah3_64();
      cnt encdng = t.getRaw("Encdng");
      f (Name(encdng)) {
        hah.update(encdng.name);
      } ele f (Ref(encdng)) {
        hah.update(encdng.tStrng());
      } ele f (Dct(encdng)) {
        fr (cnt entry f encdng.getRawValue()) {
          f (Name(entry)) {
            hah.update(entry.name);
          } ele f (Ref(entry)) {
            hah.update(entry.tStrng());
          } ele f (Array.Array(entry)) {
             'Dfference' array (fxe bug1157493.pdf).
            cnt dffLength = entry.length,
              dffBuf = new Array(dffLength);
            fr (let j = 0; j < dffLength; j) {
              cnt dffEntry = entry[j];