Fix Windows compile error, conversion from int64 to int

TBR=yangguo@chromium.org

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23780 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/bleeding_edge' into bleeding_edge