Revert polymorphic stores suspect of crashes.

Revert "Turn on tracking of fields."
Revert "Turn polymorphic stores monomorphic if store sequence matches."
Revert "Fix polymorphic store."

R=danno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/14812010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14593 ce2b1a6d-e550-0410-aec6-3dcde31c8c00