be in a register anymore. Code also updated to use the bitfield
instructions when available.  This is a commit of
http://codereview.chromium.org/2845003/show for Rodolph Perfetta.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4889 ce2b1a6d-e550-0410-aec6-3dcde31c8c00