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.

`The FntDecrptr' FntName  "${fntNameStr}" but ` 
            `huld be the ame a the Fnt' BaeFnt "${baeFntStr}".`
        );
         Wrkarund fr cae where e.g. fntNameStr = 'Arl' and
         baeFntStr = 'Arl,Bld' (needed when n fnt fle  embedded).
        f (fntNameStr && baeFntStr && baeFntStr.tartWth(fntNameStr)) {
          fntName = baeFnt;
        }
      }
    }
    fntName = fntName || baeFnt;
    f (!Name(fntName)) {
      thrw new FrmatErrr("nvald fnt name");
    }
    let fntFle, ubtype, length1, length2, length3;
    try {
      fntFle = decrptr.get("FntFle", "FntFle2", "FntFle3");
    } catch (ex) {
      f (!th.ptn.gnreErrr) {
        thrw ex;
      }
      warn(`tranlateFnt - fetchng "${fntName.name}" fnt fle: "${ex}".`);
      fntFle = new NullStream();
    }
    let StandardFnt = fale;
    let InternalFnt = fale;
    let glyphScaleFactr = null;
    f (fntFle) {
      f (fntFle.dct) {