Add Fasta tests.

pkg/fasta/test/mixin.dart

Index: pkg/fasta/test/mixin.dart
diff --git a/pkg/fasta/test/mixin.dart b/pkg/fasta/test/mixin.dart
new file mode 100644
index 0000000000000000000000000000000000000000..dbe5bf835ca7f9752283d4a7f6e3cd1e4580306d
--- /dev/null
+++ b/pkg/fasta/test/mixin.dart
@@ -0,0 +1,18 @@
+// 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.
+
+abstract class M1 {
+  m() => print("M1");
+}
+
+abstract class M2 {
+  m() => print("M2");
+}
+
+class C extends Object with M1, M2 {
+}
+
+main() {
+  new C().m();
+}