R=mstarzinger@chromium.org

BUG=crash on nosnap-debug with stress-compaction

Review URL: https://chromiumcodereview.appspot.com/12256038

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13669 ce2b1a6d-e550-0410-aec6-3dcde31c8c00