Revert "Introduce a handle zapping setting, and enable it by default for release and debug" due to performance impact.

R=jochen@chromium.org

Review URL: https://chromiumcodereview.appspot.com/18325027

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15558 ce2b1a6d-e550-0410-aec6-3dcde31c8c00