The fix is to make the code aging sequence hang off the isolate.

BUG=v8:3303
R=svenpanne@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/261953002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21165 ce2b1a6d-e550-0410-aec6-3dcde31c8c00