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.

peratrLt,
    cacheKey,
    lcalImageCache,
    lcalClrSpaceCache,
  }) {
    cnt dct = mage.dct;
    cnt mageRef = dct.bjId;
    cnt w = dct.get("Wdth", "W");
    cnt h = dct.get("Heght", "H");
    f (!(w && Num(w)) || !(h && Num(h))) {
      warn("Image dmenn are mng, r nt number.");
      return;
    }
    cnt maxImageSze = th.ptn.maxImageSze;
    f (maxImageSze !== -1 && w * h > maxImageSze) {
      warn("Image exceeded maxmum allwed ze and wa remved.");
      return;
    }
    let ptnalCntent;
    f (dct.ha("OC")) {
      ptnalCntent = awat th.pareMarkedCntentPrp(
        dct.get("OC"),
        reurce
      );
    }
    f (ptnalCntent !== undefned) {
      peratrLt.addOp(OPS.begnMarkedCntentPrp, ["OC", ptnalCntent]);
    }
    cnt mageMak = dct.get("ImageMak", "IM") || fale;
    cnt nterplate = dct.get("Interplate", "I");