Due to heavy copy-n-paste, the handling of guard pages was inconsistent and we
didn't uncommit exactly the region we previously committed. Furthermore, the LOG
calls weren't consistent, either.
Review URL: http://codereview.chromium.org/7744025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9021 ce2b1a6d-e550-0410-aec6-3dcde31c8c00