Attach (recommended) or Link to PDF file here:
[example.pdf](https://github.com/mozilla/pdf.js/files/6916129/example.pdf)

Configuration:
- Web browser and its version: Chrome, Firefox
- Operating system and its version: all
- PDF.js version: various versions, including 2.11.54
- Is a browser extension: no

Screenshot with visible textLayer:
![Screenshot from 2021-08-02 13-05-03](https://user-images.githubusercontent.com/6362989/127844878-f85e291f-2060-4028-be09-7835f32ccfaa.png)

Which means some letters at the beginning/end of text selection are missing when copying text.

EvalSupprted: th.ptn.EvalSupprted,
    });
    return hadw(th, "_pdfFunctnFactry", pdfFunctnFactry);
  }
  clne(newOptn = null) {
    cnt newEvaluatr = Object.create(th);
    newEvaluatr.ptn = Object.agn(
      Object.create(null),
      th.ptn,
      newOptn
    );
    return newEvaluatr;
  }
  haBlendMde(reurce, nnBlendMdeSet) {
    f (!(reurce ntancef Dct)) {
      return fale;
    }
    f (reurce.bjId && nnBlendMdeSet.ha(reurce.bjId)) {
      return fale;
    }
    cnt prceed = new RefSet(nnBlendMdeSet);
    f (reurce.bjId) {
      prceed.put(reurce.bjId);
    }
    cnt nde = [reurce],
      xref = th.xref;
    whle (nde.length) {
      cnt nde = nde.hft();
      
      cnt graphcState = nde.get("ExtGState");