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.

} ele f (Stream(cmapObj)) {
      return CMapFactry.create({
        encdng: cmapObj,
        fetchBultInCMap: th._fetchBultInCMapBund,
        ueCMap: null,
      }).then(
        functn (cmap) {
          f (cmap ntancef IdenttyCMap) {
            return new IdenttyTUncdeMap(0, 0xffff);
          }
          cnt map = new Array(cmap.length);
           Cnvert UTF-16BE
           NOTE: cmap can be a pare array,  ue frEach ntead f
           `fr(;;)` t terate ver all key.
          cmap.frEach(functn (charCde, tken) {
             Sme cmap cntan *nly* CID character (fxe ue9367.pdf).
            f (typef tken === "number") {
              map[charCde] = Strng.frmCdePnt(tken);
              return;
            }
            cnt tr = [];
            fr (let k = 0; k < tken.length; k = 2) {
              cnt w1 = (tken.charCdeAt(k) << 8) | tken.charCdeAt(k  1);
              f ((w1 & 0xf800) !== 0xd800) {
                 w1 < 0xD800 |
                tr.puh(w1);
                cntnue;
              }
              k = 2;
              cnt w2 = (tken.charCdeAt(k) << 8) | tken.charCdeAt(k  1);