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)

if (
      !glyph ||
      !glyph.matchesForCache(
        charcode,
        fontChar,
        unicode,
        accent,
        width,
        vmetric,
        operatorListId,
        isSpace,
        isInFont
      )
    ) {
      glyph = new Glyph(
        charcode,
        fontChar,
        unicode,
        accent,
        width,
        vmetric,
        operatorListId,
        isSpace,
        isInFont
      );
      this._glyphCache[charcode] = glyph;
    }
    return glyph;
  }
  charsToGlyphs(chars) {