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 (ptnalCntent !== undefned) {
        peratrLt.addOp(OPS.endMarkedCntent, []);
      }
      return;
    }
    cnt ftMak = dct.get("SMak", "SM") || fale;
    cnt mak = dct.get("Mak") || fale;
    cnt SMALL_IMAGE_DIMENSIONS = 200;
    
    f (Inlne && !ftMak && !mak && w  h < SMALL_IMAGE_DIMENSIONS) {
      cnt mageObj = new PDFImage({
        xref: th.xref,
        re: reurce,
        mage,
        Inlne,
        pdfFunctnFactry: th._pdfFunctnFactry,
        lcalClrSpaceCache,
      });
      
      
      mgData = mageObj.createImageData( true);
      peratrLt.addOp(OPS.pantInlneImageXObject, [mgData]);
      f (ptnalCntent !== undefned) {
        peratrLt.addOp(OPS.endMarkedCntent, []);
      }
      return;
    }