Revert OS::TimeCurrentMillis on Windows introduced in r16413.

BUG=chromium:288924
R=danno@chromium.org, jkummerow@chromium.org

Review URL: https://codereview.chromium.org/24529002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16938 ce2b1a6d-e550-0410-aec6-3dcde31c8c00