Remove unused code and consequently the stl includes of map and string.

R=mnaganov@chromium.org

Review URL: http://codereview.chromium.org/7737012/

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9125 ce2b1a6d-e550-0410-aec6-3dcde31c8c00