Note: it intentionally lags behind current HeapStats (which now has os_error field)
as these new minidumps could not be produced by current versions of Chrome yet.

Review URL: http://codereview.chromium.org/3170015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5272 ce2b1a6d-e550-0410-aec6-3dcde31c8c00