Вот такое вот получилось:

var AreaPolygon = Object.create(Polygon);
AreaPolygon.p = Polygon;
AreaPolygon.area = function(){return this.height * this.width};
Object.defineProperty(AreaPolygon, 'pname', {
  set: function(name) {this.p.__lookupSetter__('pname').call(this,name)},
  get: function() {
         return this.p.__lookupGetter__('pname').call(this) + ' My areas is '+this.area()+' square something.'
  },
  configurable:true}); // configurable - возможность изменять/переопределять

var p = AreaPolygon.create(100,200);
p.pname = 'Rectangle';
console.log(p.pname);

>> "Hi, I am a Rectangle. My areas is 20000 square something."