Support runtime check of function types.

tests/language/function_subtype_typearg3_test.dart

 // Copyright (c) 2013, 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 program for constructors and initializers.
 
-// Test that dart2js uses the right interceptor when call a method on
-// something that has type number.
+// Check function subtyping of type arguments.
 
 import 'package:expect/expect.dart';
 
-var array = [];
+class C<T> {}
+
+class I {}
+class J extends I {}
+
+typedef J f1();
+typedef I f2();
 
 main() {
-  array.add(false);
-  var x = array[0] ? 1.5 : 2;
-  Expect.isTrue(x.isEven);
-}
+  Expect.isTrue(new C<f1>() is C<f2>);
+}