Viewer:  https://mozilla.github.io/pdf.js/web/viewer.html
Chrome on Windows 10
When the attached PDF file is viewed, some of the fonts display as garbled text. 
[Arial, Courier, Times New Roman]
The file views correctly in Adobe Reader.
[fff.pdf](https://github.com/mozilla/pdf.js/files/4652174/fff.pdf)

i++;
      }
      if (this.toUnicode) {
        const charCode = getCharCode(unicode);
        if (charCode !== -1) {
          if (hasCurrentBufErrors()) {
            buffers.push(currentBuf.join(""));
            currentBuf.length = 0;
          }
          const charCodeLength = this.cMap
            ? this.cMap.getCharCodeLength(charCode)
            : 1;
          for (let j = charCodeLength - 1; j >= 0; j--) {
            currentBuf.push(String.fromCharCode((charCode >> (8 * j)) & 0xff));
          }
          continue;
        }
      }
      
      if (!hasCurrentBufErrors()) {
        buffers.push(currentBuf.join(""));
        currentBuf.length = 0;
      }
      currentBuf.push(String.fromCodePoint(unicode));
    }
    buffers.push(currentBuf.join(""));
    return buffers;
  }
}
class ErrorFont {