frog: detect when getter/setter has incorrect number of arguments.

tests/language/src/SetterDeclaration2NegativeTest.dart

Index: tests/language/src/SetterDeclaration2NegativeTest.dart
diff --git a/tests/language/src/SetterDeclaration2NegativeTest.dart b/tests/language/src/SetterDeclaration2NegativeTest.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a2df56139e87d79ca8cbf798a4b572389f2322ec
--- /dev/null
+++ b/tests/language/src/SetterDeclaration2NegativeTest.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2011, 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.
+//
+// Test that a setter has a single argument
+
+// too few arguments
+set m() { }
+
+main() {
+  m = 1;
+}
+