Fix finalization of recursive type graph with bounds (issue 25389).

tests/language/regress_25389_part.dart

+// Copyright (c) 2016, 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.
+
+part of regress_25389;
+
+abstract class ComponentState<S extends ComponentState> {}
+
+abstract class AbstractListEditorState<D,
+    S extends AbstractListEditorState<D, S>> extends ComponentState<S> {}
+
+class IssueListEditorState
+    extends AbstractListEditorState<String, IssueListEditorState>
+    implements ComponentState<IssueListEditorState> {}
+