In this case http://jsfiddle.net/25bwx5sw/6/ border-radius and overflow:hidden renders incorrect. The example speaks for itself. Issue is found in Safari 7.1/8.0 on OS X and Safari 8.0 on iOS.
<rdar://problem/18495052>
Regressed in http://trac.webkit.org/changeset/170532
Created attachment 239814 [details] Test reduction
Created attachment 239826 [details] Patch
Comment on attachment 239826 [details] Patch Clearing flags on attachment: 239826 Committed r174716: <http://trac.webkit.org/changeset/174716>
All reviewed patches have been landed. Closing bug.