Secondary changes:
- don't transfer ownership back on CNLT
- turned debugging checks back into ASSERT

Review URL: https://chromiumcodereview.appspot.com/11099064

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12699 ce2b1a6d-e550-0410-aec6-3dcde31c8c00