This allows us to optimized the EnsureInitialized() function
so it doesn't require a function call when we're running

Review URL: http://codereview.chromium.org/113121

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2048 ce2b1a6d-e550-0410-aec6-3dcde31c8c00