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 (numOfMetrics > numGlyphs) {
        info(
          `The numOfMetrics (${numOfMetrics}) should not be ` +
            `greater than the numGlyphs (${numGlyphs}).`
        );
        
        numOfMetrics = numGlyphs;
        header.data[34] = (numOfMetrics & 0xff00) >> 8;
        header.data[35] = numOfMetrics & 0x00ff;
      }
      const numOfSidebearings = numGlyphs - numOfMetrics;
      const numMissing =
        numOfSidebearings - ((metrics.length - numOfMetrics * 4) >> 1);
      if (numMissing > 0) {
        
        
        
        const entries = new Uint8Array(metrics.length + numMissing * 2);
        entries.set(metrics.data);
        if (dupFirstEntry) {
          
          entries[metrics.length] = metrics.data[2];
          entries[metrics.length + 1] = metrics.data[3];
        }
        metrics.data = entries;
      }
    }
    function sanitizeGlyph(