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.

const basicApiFileName = "basicapi.pdf";
  const basicApiFileLength = 105779; 
  const basicApiGetDocumentParams = buildGetDocumentParams(basicApiFileName);
  let CanvasFactory;
  beforeAll(function () {
    CanvasFactory = new DefaultCanvasFactory();
  });
  afterAll(function () {
    CanvasFactory = null;
  });
  function waitSome(callback) {
    const WAIT_TIMEOUT = 10;
    setTimeout(function () {
      callback();
    }, WAIT_TIMEOUT);
  }
  describe("getDocument", function () {
    it("creates pdf doc from URL-string", async function () {
      const urlStr = TEST_PDFS_PATH + basicApiFileName;
      const loadingTask = getDocument(urlStr);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      const pdfDocument = await loadingTask.promise;
      expect(typeof urlStr).toEqual("string");
      expect(pdfDocument instanceof PDFDocumentProxy).toEqual(true);
      expect(pdfDocument.numPages).toEqual(3);
      await loadingTask.destroy();
    });
    it("creates pdf doc from URL-object", async function () {
      if (isNodeJS) {
        pending("window.location is not supported in Node.js.");