Fix compilation failure on Win x64 builder introduced by r11084

R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9748004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11090 ce2b1a6d-e550-0410-aec6-3dcde31c8c00