Analog to https://github.com/adobe-fonts/source-serif-pro/issues/50, the kern feature needs `lookupflag IgnoreMarks;` inserted. Here is an illustration of the problem: <img width="544" alt="Screen Shot 2019-03-15 at 11 00 36" src="https://user-images.githubusercontent.com/2049645/54423736-ae8cf400-4711-11e9-9266-de5ca5c9a21c.png">
Analog to adobe-fonts/source-serif#50, the kern feature needs
lookupflag IgnoreMarks;inserted. Here is an illustration of the problem: