A raw pointer was used while collecting a stack trace. This was not safe as the code collecting the stack trace allocated memory.
Review URL: http://codereview.chromium.org/2147005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4712 ce2b1a6d-e550-0410-aec6-3dcde31c8c00