When adding a string with a smi value the number string cache is checked in generated code. If the there is a string value in the number string cache the resulting string is produced in generated code.
Review URL: http://codereview.chromium.org/596082

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3843 ce2b1a6d-e550-0410-aec6-3dcde31c8c00