Revert 'Port the remaining of dart:core to the unified corelib.'

corelib/unified/core/implementation/options.dart

Index: corelib/unified/core/implementation/options.dart
diff --git a/corelib/unified/core/implementation/options.dart b/corelib/unified/core/implementation/options.dart
deleted file mode 100644
index 8e73424663382ab7e04d99d5c79be240a7b6f9b8..0000000000000000000000000000000000000000
--- a/corelib/unified/core/implementation/options.dart
+++ /dev/null
@@ -1,11 +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 RuntimeOptions implements Options {
-  external List<String> get arguments();
-
-  external String get executable();
-
-  external String get script();
-}