Fix Win64 after r24758.

BUG=
TBR=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/663343002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24759 ce2b1a6d-e550-0410-aec6-3dcde31c8c00