Port r12400 (03ae62de)

Original commit message:
This is preparatory work for sharing Enum Caches.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10914025
Patch from Akos Palfi <palfia@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12417 ce2b1a6d-e550-0410-aec6-3dcde31c8c00