Fix regressions triggered by map invalidation during graph creation.

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/22807003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16150 ce2b1a6d-e550-0410-aec6-3dcde31c8c00