cache.  We now cache most of the places where Opera cache and
one or two where they do not cache for some reason.  Since
these optimizations aren't necessarily useful on real code we
may remove them if and when the Dromaeo website makes the
benchmarks harder to game.
Review URL: http://codereview.chromium.org/995005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4157 ce2b1a6d-e550-0410-aec6-3dcde31c8c00