The calling convention for keyed load IC is changed to have the key passed both in a register (r0) and on the stack.

Next steps will be first to remove the key from the stack and then pass the receiver in a register (r1).
Review URL: http://codereview.chromium.org/1937003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4584 ce2b1a6d-e550-0410-aec6-3dcde31c8c00