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)

const header = file.peekBytes(4);
  if (
     header[0] >= 1 &&
    
    
     header[3] >= 1 &&
    header[3] <= 4
  ) {
    return true;
  }
  return false;
}
function getFontFileType(file, { type, subtype, composite }) {
  let fileType, fileSubtype;
  if (isTrueTypeFile(file) || isTrueTypeCollectionFile(file)) {
    if (composite) {
      fileType = "CIDFontType2";
    } else {