This is essential for the upcoming map sharing with accessors, and we aleady
have enough machinery to handle the holes now. Furthermore, use "To" template in
2 nearby functions, and made naming a bit more consistent.

In a nutshell: This CL should have no visible effect at all at the moment.
Famous last words...

Review URL: https://chromiumcodereview.appspot.com/9594013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10919 ce2b1a6d-e550-0410-aec6-3dcde31c8c00