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.

buildGetDocumentParams(filename, {
          docBaseUrl: "http://www.example.com/test/pdfs/qwerty.pdf",
        })
      );
      const docBaseUrlPromise = docBaseUrlLoadingTask.promise.then(function (
        pdfDoc
      ) {
        return pdfDoc.getPage(1).then(function (pdfPage) {
          return pdfPage.getAnnotations();
        });
      });
      const invalidDocBaseUrlLoadingTask = getDocument(
        buildGetDocumentParams(filename, {
          docBaseUrl: "qwerty.pdf",
        })
      );
      const invalidDocBaseUrlPromise =
        invalidDocBaseUrlLoadingTask.promise.then(function (pdfDoc) {
          return pdfDoc.getPage(1).then(function (pdfPage) {
            return pdfPage.getAnnotations();
          });
        });
      const [
        defaultAnnotations,
        docBaseUrlAnnotations,
        invalidDocBaseUrlAnnotations,
      ] = await Promise.all([
        defaultPromise,
        docBaseUrlPromise,
        invalidDocBaseUrlPromise,