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 GlyphMapForStandardFonts = getGlyphMapForStandardFonts();
          for (const charCode in GlyphMapForStandardFonts) {
            map[+charCode] = GlyphMapForStandardFonts[charCode];
          }
        }
      }
      this.toFontChar = map;
    }
    amendFallbackToUnicode(properties);
    this.loadedName = fontName.split("-")[0];
    this.fontType = getFontType(type, subtype, properties.isStandardFont);
  }
  checkAndRepair(name, font, properties) {
    const VALID_TABLES = [
      "OS/2",
      "cmap",
      "head",
      "hhea",
      "hmtx",
      "maxp",
      "name",
      "post",
      "loca",
      "glyf",
      "fpgm",
      "prep",
      "cvt ",
      "CFF ",
    ];
    function readTables(file, numTables) {