Revert bad fix.

tests/language/regress_18435_test.dart

Index: tests/language/regress_18435_test.dart
===================================================================
--- tests/language/regress_18435_test.dart	(revision 36363)
+++ tests/language/regress_18435_test.dart	(working copy)
@@ -1,24 +0,0 @@
-// Copyright (c) 2014, 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.
-
-// Regression test for issue 18435.
-
-import "package:expect/expect.dart";
-
-main() {
-  const MISSING_VALUE = "MISSING_VALUE";
-
-  void foo([var p1 = MISSING_VALUE, var p2 = MISSING_VALUE]) {
-    Expect.equals("P1", p1);
-    Expect.equals("P2", p2);
-  }
-
-  void bar([var p1 = "MISSING_VALUE", var p2 = "MISSING_VALUE"]) {
-    Expect.equals("P1", p1);
-    Expect.equals("P2", p2);
-  }
-
-  foo("P1", "P2");
-  bar("P1", "P2");
-}