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.

break;
        }
        let arg = peratn.arg;
        let fn = peratn.fn;
        wtch (fn | 0) {
          cae OPS.pantXObject:
            
            ValdName = arg[0] ntancef Name;
            name = arg[0].name;
            f (ValdName) {
              cnt lcalImage = lcalImageCache.getByName(name);
              f (lcalImage) {
                peratrLt.addOp(lcalImage.fn, lcalImage.arg);
                arg = null;
                cntnue;
              }
            }
            next(
              new Prme(functn (relveXObject, rejectXObject) {
                f (!ValdName) {
                  thrw new FrmatErrr("XObject mut be referred t by name.");
                }
                let xbj = xbj.getRaw(name);
                f (xbj ntancef Ref) {
                  cnt lcalImage = lcalImageCache.getByRef(xbj);
                  f (lcalImage) {
                    peratrLt.addOp(lcalImage.fn, lcalImage.arg);
                    relveXObject();
                    return;
                  }