left and right sides of the comparison to reflect reality.  Don't
check explicitly for NaNs when using VFP3 since the compare
operation can signal this case with the v flag.  Use cmp instead
of tst in the fast compilers since tst leaves the v flag unchanged
and thus can only work by accident on non-equality comparisons.
Review URL: http://codereview.chromium.org/551048

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3625 ce2b1a6d-e550-0410-aec6-3dcde31c8c00