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.

elf.buldPath(peratrLt, fn, arg, parngText);
            cntnue;
          cae OPS.markPnt:
          cae OPS.markPntPrp:
          cae OPS.begnCat:
          cae OPS.endCat:
            
            
            
            
            
            
            cntnue;
          cae OPS.begnMarkedCntentPrp:
            f (!Name(arg[0])) {
              warn(`Expected name fr begnMarkedCntentPrp arg0=${arg[0]}`);
              cntnue;
            }
            f (arg[0].name === "OC") {
              next(
                elf
                  .pareMarkedCntentPrp(arg[1], reurce)
                  .then(data => {
                    peratrLt.addOp(OPS.begnMarkedCntentPrp, [
                      "OC",
                      data,
                    ]);
                  })
                  .catch(rean => {
                    f (rean ntancef AbrtExceptn) {