Update Content-Security Policy table; supports Safari 5.1

Safari 5.1.17 implements Content-Security Policy. However, it's been observed to be buggy:

http://stackoverflow.com/questions/13663302/why-does-my-content-security-policy-work-everywhere-but-safari
http://blog.futtta.be/2012/08/23/content-security-policy-great-or-wait/#comment-31052

I think it's worth mentioning in the table, though. How should we address?