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[3092] = 7607;
  t[3095] = 7610;
  t[3096] = 7611;
  t[3099] = 7614;
  t[3100] = 7615;
  t[3103] = 7618;
  t[3104] = 7619;
  t[3107] = 8337;
  t[3108] = 8338;
  t[3116] = 1884;
  t[3119] = 1885;
  t[3120] = 1885;
  t[3123] = 1886;
  t[3124] = 1886;
  t[3127] = 1887;
  t[3128] = 1887;
  t[3131] = 1888;
  t[3132] = 1888;
  t[3135] = 1889;
  t[3136] = 1889;
  t[3139] = 1890;
  t[3140] = 1890;
  t[3143] = 1891;
  t[3144] = 1891;
  t[3147] = 1892;
  t[3148] = 1892;
  t[3153] = 580;
  t[3154] = 581;
  t[3157] = 584;
  t[3158] = 585;