Calculate 2d area of a polygon in wgs84

[khoiboo]

I have a polygon in wgs84. If I use the method polygon.calculateArea2D(), the result is in angular units (according to the documentation). Naturally I would like to have the results in square meters or similar.

It seems to me that the polygon has to be projected to webMercator spatial reference system. However, I cannot find such method in the Polygon's list of methods or the static methods of GeometryEngine.

[randallwhitman]

cross-reference #212