fdb4c100e0
_fatal was a private function in dart:core which was called from a different library (dart:async). It's not clear how it was supposed to work or if it even did. The uses in dart:async don't appear to be covered by tests. Move it to dart:_internal which exists exactly for sharing things between the dart: libraries. BUG= R=kustermann@google.com Review-Url: https://codereview.chromium.org/2684033006 .