Otherwise we may crash.

BUG=None
LOG=N
R=alph@chromium.org, hpayer@chromium.org

Review URL: https://codereview.chromium.org/169773002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19437 ce2b1a6d-e550-0410-aec6-3dcde31c8c00