set pointBackgroundColor in radar sample

[kurkle]

Closes #5176

[benmccann]

I tried editing this line locally. It doesn't seem like it's doing anything or maybe I'm just missing something. But whether I call it pointBorderColor or pointBackgroundColor or remove it, the chart looks exactly the same to me in all cases

I'd rather just remove this line if it doesn't do anything

[kurkle]

@benmccann notice it's in the addDataset button code.

[benmccann]

Yes, I tested pressing the add dataset button. It still does nothing as far as I can tell

[kurkle]

Yes, I tested pressing the add dataset button. It still does nothing as far as I can tell

Made a pen to demonstrate (with larger pointRadius to make it more obvious)
https://codepen.io/kurkle/pen/daGpRe

[benmccann]

Thanks!