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 pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      const operatorList = await pdfPage.getOperatorList();
      expect(operatorList.fnArray.length).toBeGreaterThan(20);
      expect(operatorList.argsArray.length).toBeGreaterThan(20);
      expect(operatorList.lastChunk).toEqual(true);
      
      
      expect(operatorList.fnArray.includes(OPS.beginAnnotation)).toEqual(true);
      expect(operatorList.fnArray.includes(OPS.endAnnotation)).toEqual(true);
      await loadingTask.destroy();
    });
    it("gets operator list, with `annotationMode`-option", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("evaljs.pdf"));
      const pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(2);
      pdfDoc.annotationStorage.setValue("30R", { value: "test" });
      pdfDoc.annotationStorage.setValue("31R", { value: true });
      const opListAnnotDisable = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.DISABLE,
      });
      expect(opListAnnotDisable.fnArray.length).toEqual(0);
      expect(opListAnnotDisable.argsArray.length).toEqual(0);
      expect(opListAnnotDisable.lastChunk).toEqual(true);
      const opListAnnotEnable = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE,
      });
      expect(opListAnnotEnable.fnArray.length).toBeGreaterThan(150);
      expect(opListAnnotEnable.argsArray.length).toBeGreaterThan(150);