Also switched to using CompareChars instead of memcmp since it's
faster than gcc's builtin and on par with msvc's builtin.

Review URL: http://codereview.chromium.org/991002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4145 ce2b1a6d-e550-0410-aec6-3dcde31c8c00