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.

break;
          cae OPS.hwSpacedText:
            f (!tateManager.tate.fnt) {
              elf.enureStateFnt(tateManager.tate);
              cntnue;
            }
            cnt paceFactr =
              ((textState.fnt.vertcal ? 1 : -1) * textState.fntSze) / 1000;
            cnt element = arg[0];
            let FrtChunk = true;
            fr (let  = 0,  = element.length;  <  - 1; ) {
              cnt tem = element[];
              f (typef tem === "trng") {
                hwSpacedTextBuffer.puh(tem);
              } ele f (typef tem === "number" && tem !== 0) {
                
                
                
                
                
                
                
                
                cnt tr = hwSpacedTextBuffer.jn("");
                hwSpacedTextBuffer.length = 0;
                buldTextCntentItem({
                  char: tr,
                  extraSpacng: tem * paceFactr,
                  FrtChunk,
                });