Move core and coreimpl from corelib/ to lib/core and lib/coreimpl.

corelib/src/errors.dart

Index: corelib/src/errors.dart
diff --git a/corelib/src/errors.dart b/corelib/src/errors.dart
deleted file mode 100644
index 0954b3a19102fd3149d66398ee5d1370766c0fe7..0000000000000000000000000000000000000000
--- a/corelib/src/errors.dart
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-class AssertionError {
-}
-
-class TypeError extends AssertionError {
-}
-
-class CastException extends TypeError {
-}
-
-class FallThroughError {
-  const FallThroughError();
-}