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.

} else if (flag & 32) {
          yLength = 0;
        }
        const xyLength = xLength + yLength;
        coordinatesLength += xyLength;
        if (flag & 8) {
          const repeat = glyf[j++];
          i += repeat;
          coordinatesLength += repeat * xyLength;
        }
      }
      
      if (coordinatesLength === 0) {
        return glyphProfile;
      }
      let glyphDataLength = j + coordinatesLength;
      if (glyphDataLength > glyf.length) {
        
        return glyphProfile;
      }
      if (!hintsValid && instructionsLength > 0) {
        dest.set(glyf.subarray(0, instructionsStart), destStart);
        dest.set([0, 0], destStart + instructionsStart);
        dest.set(
          glyf.subarray(instructionsEnd, glyphDataLength),
          destStart + instructionsStart + 2
        );
        glyphDataLength -= instructionsLength;
        if (glyf.length - glyphDataLength > 3) {
          glyphDataLength = (glyphDataLength + 3) & ~3;