Make initializing formal access available by default

tests/language/parameter_initializer5_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.
+//
+// DartOptions=--initializing-formal-access
+// VMOptions=--initializing-formal-access
 
-// Fails because this.x parameter is used in initializer expression.
+// Use the this.x parameter in an initializer expression.
 
 class Foo {
   var x, y;
   Foo(this.x): y = x { }
 }
 
-
 main() {
   new Foo(12);
 }