code: function(way) { 
          var poly_shaped = false;
          var poly_tags = false;
          
          if (way.nodes[0] == way.nodes[way.nodes.length - 1]) {
              poly_shaped = true;
          }
          if (this.checkTags) {
              for(var key in way.tags) {
                  if (this.areaTags[key]) {
                      poly_tags = true;
                      break;
                  }
              }
          }    
          return poly_shaped && (this.checkTags ? poly_tags : true);            
      }
docs: Method: isWayArea
  Given a way object from getWays, check whether the tags and geometry
  indicate something is an area.
  
  Returns:
  {Boolean}