Add Fasta tests.

pkg/fasta/test/default_values.dart

Index: pkg/fasta/test/default_values.dart
diff --git a/pkg/fasta/test/default_values.dart b/pkg/fasta/test/default_values.dart
new file mode 100644
index 0000000000000000000000000000000000000000..de8ccc5df3c3ae1e980a989713babc435727e6b7
--- /dev/null
+++ b/pkg/fasta/test/default_values.dart
@@ -0,0 +1,9 @@
+// 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.
+
+topLevel([a = 42]) => a;
+
+main() {
+  print(topLevel());
+}