Revert "Allow code to be cached in shared maps." due to GC stress crashes.

TBR=ulan@chromium.org

Review URL: https://chromiumcodereview.appspot.com/25084005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17022 ce2b1a6d-e550-0410-aec6-3dcde31c8c00