area method
Return area (in sqm) of given polygon geometry.
Adapted from https://github.com/porn/area
Implementation
num area(Geometry geometry) {
num _area = 0;
var geomCount = geometry.getNumGeometries();
for (var i = 0; i < geomCount; i++) {
var geom = geometry.getGeometryN(i);
_area += _polygonArea(geom as Polygon);
}
return _area;
}