Fix Mac build after r24676.

BUG=v8:3638
LOG=n
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/659253002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24679 ce2b1a6d-e550-0410-aec6-3dcde31c8c00