cubicTo method
Add a cubicTo to the path
Implementation
@override
void cubicTo(PointT c1, PointT c2, PointT p, bool shorthand) {
if (shorthand) {
_result.write('S ');
} else {
_result.write('C ${c1.x} ${c1.y} ');
}
_result.write('${c2.x} ${c2.y} ${p.x} ${p.y} ');
}