Change keyed store IC interface on x64 to take value, key, and receiver in registers rather than on the stack.
Review URL: http://codereview.chromium.org/2111011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4692 ce2b1a6d-e550-0410-aec6-3dcde31c8c00