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 { numFonts, offsetTable } = readTrueTypeCollectionHeader(ttc);
      const fontNameParts = fontName.split("+");
      let fallbackData;
      for (let i = 0; i < numFonts; i++) {
        ttc.pos = (ttc.start || 0) + offsetTable[i];
        const potentialHeader = readOpenTypeHeader(ttc);
        const potentialTables = readTables(ttc, potentialHeader.numTables);
        if (!potentialTables.name) {
          throw new FormatError(
            'TrueType Collection font must contain a "name" table.'
          );
        }
        const nameTable = readNameTable(potentialTables.name);
        for (let j = 0, jj = nameTable.length; j < jj; j++) {
          for (let k = 0, kk = nameTable[j].length; k < kk; k++) {
            const nameEntry =
              nameTable[j][k] && nameTable[j][k].replace(/\s/g, "");
            if (!nameEntry) {
              continue;
            }
            if (nameEntry === fontName) {
              return {
                header: potentialHeader,
                tables: potentialTables,
              };
            }
            if (fontNameParts.length < 2) {
              continue;
            }
            for (const part of fontNameParts) {