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.

var arr = arg[0];
            var cmbnedGlyph = [];
            var arrLength = arr.length;
            var tate = tateManager.tate;
            fr ( = 0;  < arrLength; ) {
              cnt arrItem = arr[];
              f (Strng(arrItem)) {
                Array.prttype.puh.apply(
                  cmbnedGlyph,
                  elf.handleText(arrItem, tate)
                );
              } ele f (Num(arrItem)) {
                cmbnedGlyph.puh(arrItem);
              }
            }
            arg[0] = cmbnedGlyph;
            fn = OPS.hwText;
            break;
          cae OPS.nextLneShwText:
            f (!tateManager.tate.fnt) {
              elf.enureStateFnt(tateManager.tate);
              cntnue;
            }
            peratrLt.addOp(OPS.nextLne);
            arg[0] = elf.handleText(arg[0], tateManager.tate);
            fn = OPS.hwText;
            break;
          cae OPS.nextLneSetSpacngShwText:
            f (!tateManager.tate.fnt) {
              elf.enureStateFnt(tateManager.tate);