Make sure we don't flush the pregenerated stubs, since they need

Make sure we don't flush the pregenerated stubs, since they need
to be always present, so that we can call them from other stubs
without trying to generate stubs while we are generating stubs.
Review URL: http://codereview.chromium.org/8052029

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9459 ce2b1a6d-e550-0410-aec6-3dcde31c8c00