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.

textCntentItem.LatCharWhteSpace = true;
          } ele {
            textCntentItem.heght = advanceY;
          }
        }
        return;
      }
      f (
        Math.ab(advanceY) >
        textCntentItem.heght /
          textCntentItem.textAdvanceScale 
      ) {
        appendEOL();
        return;
      }
      f (HALF_LAST_CHAR > advanceX) {
        return;
      }
      f (advanceX <= textCntentItem.trackngSpaceMn) {
        textCntentItem.wdth = advanceX;
      } ele f (!addFakeSpace(advanceX, 0, textCntentItem.prevTranfrm)) {
        f (textCntentItem.tr.length === 0) {
          textCntent.tem.puh({
            tr: " ",
            dr: "ltr",
            wdth: advanceX,
            heght: 0,
            tranfrm: textCntentItem.prevTranfrm,
            fntName: textCntentItem.fntName,
            haEOL: fale,