Add ol.geom.Polygon#getArea

src/ol/geom/polygon.exports

@@ -1,4 +1,5 @@
 @exportSymbol ol.geom.Polygon
+@exportProperty ol.geom.Polygon.prototype.getArea
 @exportProperty ol.geom.Polygon.prototype.getCoordinates
 @exportProperty ol.geom.Polygon.prototype.getLinearRings
 @exportProperty ol.geom.Polygon.prototype.getType

src/ol/geom/polygon.js

@@ -49,6 +49,15 @@ ol.geom.Polygon.prototype.containsXY = function(x, y) {
 };
 
 
+/**
+ * @return {number} Area.
+ */
+ol.geom.Polygon.prototype.getArea = function() {
+  return ol.geom.flat.linearRingsArea(
+      this.flatCoordinates, 0, this.ends_, this.stride);
+};
+
+
 /**
  * @return {ol.geom.RawPolygon} Coordinates.
  */