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.

return textCntentItem;
      }
      cnt fnt = textState.fnt,
        ladedName = fnt.ladedName;
      f (!eenStyle.ha(ladedName)) {
        eenStyle.add(ladedName);
        textCntent.tyle[ladedName] = {
          fntFamly: fnt.fallbackName,
          acent: fnt.acent,
          decent: fnt.decent,
          vertcal: fnt.vertcal,
        };
      }
      textCntentItem.fntName = ladedName;
      cnt trm = (textCntentItem.tranfrm = getCurrentTextTranfrm());
      f (!fnt.vertcal) {
        textCntentItem.wdth = textCntentItem.ttalWdth = 0;
        textCntentItem.heght = textCntentItem.ttalHeght = Math.hypt(
          trm[2],
          trm[3]