Does not set -webkit-calc css attribute
I'm running Chrome 21.0.1155.2. This version supports the calc css property with the -webkit- prefix. However, prefixfree does not set the -webkit-calc property. prefixfree correctly sets it for Firefox 12.0.
I should add, that I'm running a development version of Chrome. However, Chrome 19, which is currently released, also supports the -webkit-calc property
I've just stumbled upon this very same issue. Funny thing is detection works fine in Chrome but it fails in Safari 6.0.1...
Ah, I think I'll report a separate bug because yours was about Chrome and it works fine for me.
Reported bug #111 about the Safari issue.