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.

let totalPages = matchesPerPage.length;
    for (let i = totalPages - 1; i >= 0; i--) {
      if (matchesPerPage[i] > 0) {
        totalPages = i + 1;
        break;
      }
    }
    const totalMatches = matchesPerPage.reduce((a, b) => {
      return a + b;
    });
    eventBus.on(
      "updatefindmatchescount",
      function onUpdateFindMatchesCount(evt) {
        if (pdfFindController.pageMatches.length !== totalPages) {
          return;
        }
        eventBus.off("updatefindmatchescount", onUpdateFindMatchesCount);
        expect(evt.matchesCount.total).toBe(totalMatches);
        for (let i = 0; i < totalPages; i++) {
          expect(pdfFindController.pageMatches[i].length).toEqual(
            matchesPerPage[i]
          );
        }
        expect(pdfFindController.selected.pageIdx).toEqual(
          selectedMatch.pageIndex
        );
        expect(pdfFindController.selected.matchIdx).toEqual(
          selectedMatch.matchIndex