Webkit keeps prefixes usually because it is not implemented fully and it is an experimental feature. They began unprefixing flexbox in Sept. 2014, I don't know

Webkit keeps prefixes usually because it is not implemented fully and it is an experimental feature. They began unprefixing flexbox in Sept. 2014, I don't know when it's gonna ship. Though, its super unfair that the Web Inspector in Webkit uses unprefixed Flexbox (http://trac.webkit.org http://trac.webkit.org revision 173707).