[BUG] lineTension doesn't work for Radar chart type.

[KoyoSE]

Current Behavior

lineTension option doesn't work for Radar chart type.
tension work.

Setting of this chart is lineTension = 0.5

Possible Solution

With this change, I think that this issue can be fixed.

https://github.com/chartjs/Chart.js/blob/master/src/controllers/controller.radar.js#L98

tension: custom.tension ? custom.tension : helpers.getValueOrDefault(dataset.lineTension, ....

Steps to Reproduce (for bugs)

jsfiddle

Environment

Chart.js version : 2.4.0
Browser name and version : Microsoft Edge 38.14393.0.0
Link to my project : https://jsfiddle.net/wzvhcpfy/2/

[etimberg]

@KoyoSE lineTension is the correct property to use. It looks like the line chart has some code to port the old tension option.