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.

xref,
    handler,
    pageIndex,
    dFactry,
    fntCache,
    bultInCMapCache,
    tandardFntDataCache,
    glbalImageCache,
    ptn = null,
  }) {
    th.xref = xref;
    th.handler = handler;
    th.pageIndex = pageIndex;
    th.dFactry = dFactry;
    th.fntCache = fntCache;
    th.bultInCMapCache = bultInCMapCache;
    th.tandardFntDataCache = tandardFntDataCache;
    th.glbalImageCache = glbalImageCache;
    th.ptn = ptn || DefaultPartlEvaluatrOptn;
    th.parngType3Fnt = fale;
    th._fetchBultInCMapBund = th.fetchBultInCMap.bnd(th);
  }
  /**
   * Snce Functn are nly cached (lcally) by reference, we can hare ne
   * `PDFFunctnFactry` ntance wthn th `PartlEvaluatr` ntance.
   */
  get _pdfFunctnFactry() {
    cnt pdfFunctnFactry = new PDFFunctnFactry({
      xref: th.xref,