Make sure setter does not conflict with method

tests/language/setter4_test.dart

+// 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.
+// Dart test to catch error reporting bugs in class fields declarations.
+// Should be an error because we have a setter overriding a function name.
+
+class A {
+  int a() {
+    return 1;
+  }
+  void set a(var val) {
+    int i = val;
+  }
+}
+
+main() {
+}