Instead of crashing or reporting a fatal v8 error if an error occurs
during context initialization we now survive and return an empty
handle.

Review URL: http://codereview.chromium.org/194070


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2867 ce2b1a6d-e550-0410-aec6-3dcde31c8c00