User analytics based on feature support instead of browser versions, etc

If you have done any CSS or JavaScript you should know to rely on browser features and not brand and version.

if supports websockets do something

and not

if not ie do something

Question: Do you know if any ‘modern’ analytics tools that registers these features?

All I see is: Browser, Version, JavaScript support, resolution, all that which shouldn’t matter. I would sure like to know for instance what percentage of m开发者_运维技巧y users that supported ‘border-radius’.

Sure I could gather that info myself, but why do it if somebody else did already :)