Drive-by cleanup: remove unused elements_kind_ field in CallNew.

BUG=chromium:416558
LOG=n
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/595333002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24211 ce2b1a6d-e550-0410-aec6-3dcde31c8c00