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

corelib/src/hashable.dart

Index: corelib/src/hashable.dart
diff --git a/corelib/src/hashable.dart b/corelib/src/hashable.dart
deleted file mode 100644
index b0578c0b6b9cc86048a57087956cb86271c4c42f..0000000000000000000000000000000000000000
--- a/corelib/src/hashable.dart
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright (c) 2011, 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.
-
-// Dart core library.
-
-abstract class Hashable {
-  factory Hashable._uninstantiable() {
-    throw const UnsupportedOperationException(
-        "abstract class Hashable cannot be instantiated");
-  }
-  abstract int hashCode();
-}