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.

});
/
/
/
const getGlyphMapForStandardFonts = getLookupTableFactory(function (t) {
  t[2] = 10;
  t[3] = 32;
  t[4] = 33;
  t[5] = 34;
  t[6] = 35;
  t[7] = 36;
  t[8] = 37;
  t[9] = 38;
  t[10] = 39;
  t[11] = 40;
  t[12] = 41;
  t[13] = 42;
  t[14] = 43;
  t[15] = 44;
  t[16] = 45;
  t[17] = 46;
  t[18] = 47;
  t[19] = 48;
  t[20] = 49;
  t[21] = 50;
  t[22] = 51;
  t[23] = 52;
  t[24] = 53;
  t[25] = 54;
  t[26] = 55;