The ia32 version was implemented in r3542 and r3543. The x64 was implementeed in r3740, r3741 and r3742.

Minor tweaks to the is32 and x64 code as well.
Review URL: http://codereview.chromium.org/1575035

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4409 ce2b1a6d-e550-0410-aec6-3dcde31c8c00