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 (
        properties.hasEncoding &&
        !this.isSymbolicFont &&
        ((cmapPlatformId === 3 && cmapEncodingId === 1) ||
          (cmapPlatformId === 1 && cmapEncodingId === 0))
      ) {
        const glyphsUnicodeMap = getGlyphsUnicode();
        for (let charCode = 0; charCode < 256; charCode++) {
          let glyphName;
          if (this.differences[charCode] !== undefined) {
            glyphName = this.differences[charCode];
          } else if (baseEncoding.length && baseEncoding[charCode] !== "") {
            glyphName = baseEncoding[charCode];
          } else {
            glyphName = StandardEncoding[charCode];
          }
          if (!glyphName) {
            continue;
          }
          
          const standardGlyphName = recoverGlyphName(
            glyphName,
            glyphsUnicodeMap
          );
          let unicodeOrCharCode;
          if (cmapPlatformId === 3 && cmapEncodingId === 1) {
            unicodeOrCharCode = glyphsUnicodeMap[standardGlyphName];
          } else if (cmapPlatformId === 1 && cmapEncodingId === 0) {
            
            unicodeOrCharCode = MacRomanEncoding.indexOf(standardGlyphName);