Added utility function for capturing stack traces so that efficient
stack trace collection works for custom errors too, not just built-in
ones.

Review URL: http://codereview.chromium.org/159403


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2541 ce2b1a6d-e550-0410-aec6-3dcde31c8c00