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["TimesNewRomanPSMT-Italic"] = "Times-Italic";
});
const getFontNameToFileMap = getLookupTableFactory(function (t) {
  t.Courier = "FoxitFixed.pfb";
  t["Courier-Bold"] = "FoxitFixedBold.pfb";
  t["Courier-BoldOblique"] = "FoxitFixedBoldItalic.pfb";
  t["Courier-Oblique"] = "FoxitFixedItalic.pfb";
  t.Helvetica = "FoxitSans.pfb";
  t["Helvetica-Bold"] = "FoxitSansBold.pfb";
  t["Helvetica-BoldOblique"] = "FoxitSansBoldItalic.pfb";
  t["Helvetica-Oblique"] = "FoxitSansItalic.pfb";
  t["Times-Roman"] = "FoxitSerif.pfb";
  t["Times-Bold"] = "FoxitSerifBold.pfb";
  t["Times-BoldItalic"] = "FoxitSerifBoldItalic.pfb";
  t["Times-Italic"] = "FoxitSerifItalic.pfb";
  t.Symbol = "FoxitSymbol.pfb";
  t.ZapfDingbats = "FoxitDingbats.pfb";
  t["LiberationSans-Regular"] = "LiberationSans-Regular.ttf";
  t["LiberationSans-Bold"] = "LiberationSans-Bold.ttf";
  t["LiberationSans-Italic"] = "LiberationSans-Italic.ttf";
  t["LiberationSans-BoldItalic"] = "LiberationSans-BoldItalic.ttf";
});
/**
 * Holds the map of the non-standard fonts that might be included as
 * a standard fonts without glyph data.
 */
const getNonStdFontMap = getLookupTableFactory(function (t) {
  t.Calibri = "Helvetica";
  t["Calibri-Bold"] = "Helvetica-Bold";
  t["Calibri-BoldItalic"] = "Helvetica-BoldOblique";