GeoPolygon constructor
Create a polygon from an outerRing
and a list of holes
The outer ring must be a closed ring, and the holes must be non-overlapping
closed rings inside the outer ring.
Implementation
GeoPolygon(this.outerRing, [this.holes = const []]) {
outerRing.validate();
for (final hole in holes) {
hole.validate();
}
}