Import rasta tests.

pkg/fasta/test/rasta/duplicated_mixin.dart

Index: pkg/fasta/test/rasta/duplicated_mixin.dart
diff --git a/pkg/fasta/test/rasta/duplicated_mixin.dart b/pkg/fasta/test/rasta/duplicated_mixin.dart
new file mode 100644
index 0000000000000000000000000000000000000000..08368cfe449dab0e4c25587c302575b44ea83f57
--- /dev/null
+++ b/pkg/fasta/test/rasta/duplicated_mixin.dart
@@ -0,0 +1,10 @@
+// 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.md file.
+
+class Mixin {
+  var field;
+}
+
+class A extends Object with Mixin, Mixin {
+}