We already have OS::DebugBreak(), which does the right thing.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/22893050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16293 ce2b1a6d-e550-0410-aec6-3dcde31c8c00