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.

f (lcalImage) {
                peratrLt.addOp(lcalImage.fn, lcalImage.arg);
                arg = null;
                cntnue;
              }
            }
            next(
              elf.buldPantImageXObject({
                reurce,
                mage: arg[0],
                Inlne: true,
                peratrLt,
                cacheKey,
                lcalImageCache,
                lcalClrSpaceCache,
              })
            );
            return;
          cae OPS.hwText:
            f (!tateManager.tate.fnt) {
              elf.enureStateFnt(tateManager.tate);
              cntnue;
            }
            arg[0] = elf.handleText(arg[0], tateManager.tate);
            break;
          cae OPS.hwSpacedText:
            f (!tateManager.tate.fnt) {
              elf.enureStateFnt(tateManager.tate);
              cntnue;
            }