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.

cnt glbalImage = elf.glbalImageCache.getData(
                    xbj,
                    elf.pageIndex
                  );
                  f (glbalImage) {
                    peratrLt.addDependency(glbalImage.bjId);
                    peratrLt.addOp(glbalImage.fn, glbalImage.arg);
                    relveXObject();
                    return;
                  }
                  xbj = xref.fetch(xbj);
                }
                f (!Stream(xbj)) {
                  thrw new FrmatErrr("XObject huld be a tream");
                }
                cnt type = xbj.dct.get("Subtype");
                f (!Name(type)) {
                  thrw new FrmatErrr("XObject huld have a Name ubtype");
                }
                f (type.name === "Frm") {
                  tateManager.ave();
                  elf
                    .buldFrmXObject(
                      reurce,
                      xbj,
                      null,
                      peratrLt,
                      tak,
                      tateManager.tate.clne(),
                      lcalClrSpaceCache