Support runtime check of function types.

tests/language/function_subtype_closure0_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 implicit setters in checked mode do a type check.
+// Check function subtyping of static functions.
 
-import "package:expect/expect.dart";
+import 'package:expect/expect.dart';
 
-class A {
-  C c;
+typedef I<T> f2<T>();
+
+class X {
+  static J<bool> f1() => null;
 }
 
-class B extends A {
+class C<T> {
+  C(f2<T> f);
 }
 
-class C {
-}
-
-var array = [new B()];
+class I<T> {}
+class J<T> extends I<int> {}
 
 main() {
-  array[0].c = new C();
+
   bool inCheckedMode = false;
   try {
     String a = 42;
   } catch (e) {
     inCheckedMode = true;
   }
+
+  new C<int>(X.f1);
   if (inCheckedMode) {
-    Expect.throws(() => array[0].c = new B(), (e) => e is TypeError);
+    Expect.throws(() => new C<bool>(X.f1), (e) => true);
   }
-}
+}