This makes the code have the same structore as on IA32 and ARM, and will also support possible fast adding a smi and string where the string is to the right and fast adding of String objects.
Review URL: http://codereview.chromium.org/6542060

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6892 ce2b1a6d-e550-0410-aec6-3dcde31c8c00