The crankshaft code now only relies on the type recording binary operation stub.

Added check for overwritable heap number in the type recording binary operation stub.
Review URL: http://codereview.chromium.org/6529050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6823 ce2b1a6d-e550-0410-aec6-3dcde31c8c00