an error message that needs to be generated and reported. This change
hides all of the error information from JavaScript code so user
callbacks cannot get hold of it.

Review URL: http://codereview.chromium.org/6368051

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6574 ce2b1a6d-e550-0410-aec6-3dcde31c8c00