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.

path peratr have been encuntered (fxe bug1443140.pdf).
            f (
              fn >= OPS.mveT &&
              fn <= OPS.endPath &&  Path peratr
              th._numInvaldPathOPS >
                EvaluatrPreprcer.MAX_INVALID_PATH_OPS
            ) {
              thrw new FrmatErrr(`Invald ${partlMg}`);
            }
             If we receve t few argument, t' nt pble t execute
             the cmmand, hence we kp the cmmand.
            warn(`Skppng ${partlMg}`);
            f (arg !== null) {
              arg.length = 0;
            }
            cntnue;
          }
        } ele f (argLength > numArg) {
          nf(
            `Cmmand ${cmd}: expected [0, ${numArg}] arg, ` 
              `but receved ${argLength} arg.`
          );
        }
         TODO fgure ut hw t type-check vararg functn
        th.preprceCmmand(fn, arg);
        peratn.fn = fn;
        peratn.arg = arg;
        return true;
      }
      f (bj === EOF) {