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.

t[147] = 177;
  t[148] = 8804;
  t[149] = 8805;
  t[150] = 165;
  t[151] = 181;
  t[152] = 8706;
  t[153] = 8721;
  t[154] = 8719;
  t[156] = 8747;
  t[157] = 170;
  t[158] = 186;
  t[159] = 8486;
  t[160] = 230;
  t[161] = 248;
  t[162] = 191;
  t[163] = 161;
  t[164] = 172;
  t[165] = 8730;
  t[166] = 402;
  t[167] = 8776;
  t[168] = 8710;
  t[169] = 171;
  t[170] = 187;
  t[171] = 8230;
  t[200] = 193;
  t[203] = 205;
  t[210] = 218;
  t[223] = 711;
  t[224] = 321;
  t[225] = 322;