rotate polygon around point in leaflet map

I have an issue, in my leaflet map I've created a triangle from polygon:

var polygon = L.polygon([     [parseFloat(decimal_lat),parseFloat(decimal_lon)],     [parseFloat(decimal_lat) + 1, parseFloat(decimal_lon) - 1],     [parseFloat(decimal_lat) + 1, parseFloat(decimal_lon) + 1] ],           {            color:'green'    });polygon.addTo(map);

and I want to rotate this polygon around Point[decimal_lon, decimal_lat]. But I'm not able to solve it..
I've created DEMO, where I'm rotating polynom the same I want to rotate my triangle (polygon) to show you my problem.