RadarChart - add straight "spider" lines (similar to CircularGridLines)

Right now, it's possible to create a "spider" chart by using RadarChart and adding invalid data. See the "Radar Chart with Tooltips" showcase for an example:

In this example, the chart uses 6 dummy data entries to draw the 6 polygons before adding the real polygon. This is a little clunky.

It would be nice to have something like CircularGridLines (maybe StraightCircularGridLines?) to optionally add to the RadarChart. Consider the following example: a radar chart has 5 domains, each have a range of 0-5. The data you want to represent has a perfect 5 in all 5 domains. The CircularGridLines would make it look like the data is lacking - not a perfect 5/5/5 - due to the space between the polygon's straight lines and the rounded grid lines. Straight lines would more accurately depict the data.