Support runtime check of function types.

tests/language/function_subtype_bound_closure3_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.
+
+// Check function subtyping for generic bound closures.
+
+import 'package:expect/expect.dart';
+
+typedef void Foo(bool a, [String b]);
+typedef void Bar(bool a, [String b]);
+typedef void Baz(bool a, {String b});
+typedef int Boz(bool a);
+
+class C<T> {
+  void foo(T a, [String b]) {}
+  void baz(T a, {String b}) {}
+
+  void test(String nameOfT, bool expectedResult) {
+    Expect.equals(expectedResult, foo is Foo, 'C<$nameOfT>.foo is Foo');
+    Expect.equals(expectedResult, foo is Bar, 'C<$nameOfT>.foo is Bar');
+    Expect.isFalse(foo is Baz, 'C<$nameOfT>.foo is Baz');
+    Expect.isFalse(foo is Boz, 'C<$nameOfT>.foo is Boz');
+
+    Expect.isFalse(baz is Foo, 'C<$nameOfT>.baz is Foo');
+    Expect.isFalse(baz is Bar, 'C<$nameOfT>.baz is Bar');
+    Expect.equals(expectedResult, baz is Baz, 'C<$nameOfT>.baz is Baz');
+    Expect.isFalse(baz is Boz, 'C<$nameOfT>.baz is Boz');
+  }
+}
+
+main() {
+  new C<bool>().test('bool', true);
+  new C<int>().test('int', false);
+  new C().test('dynamic', true);
+}