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.

it("gets fingerprints", function () {
      expect(pdfDocument.fingerprints).toEqual([
        "ea8b35919d6279a369e835bde778611b",
        null,
      ]);
    });
    it("gets fingerprints, from modified document", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("annotation-tx.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      expect(pdfDoc.fingerprints).toEqual([
        "3ebd77c320274649a68f10dbf3b9f882",
        "e7087346aa4b4ae0911c1f1643b57345",
      ]);
      await loadingTask.destroy();
    });
    it("gets page", async function () {
      const data = await pdfDocument.getPage(1);
      expect(data instanceof PDFPageProxy).toEqual(true);
      expect(data.pageNumber).toEqual(1);
    });
    it("gets non-existent page", async function () {
      let outOfRangePromise = pdfDocument.getPage(100);
      let nonIntegerPromise = pdfDocument.getPage(2.5);
      let nonNumberPromise = pdfDocument.getPage("1");
      outOfRangePromise = outOfRangePromise.then(
        function () {
          throw new Error("shall fail for out-of-range pageNumber parameter");
        },