Support runtime check of function types.

tests/language/function_subtype_bound_closure0_test.dart

Index: tests/language/function_subtype_bound_closure0_test.dart
diff --git a/tests/language/function_subtype_bound_closure0_test.dart b/tests/language/function_subtype_bound_closure0_test.dart
new file mode 100644
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+++ b/tests/language/function_subtype_bound_closure0_test.dart
@@ -0,0 +1,40 @@
+// 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 bound closures.
+
+import 'package:expect/expect.dart';
+
+typedef int Foo(bool a, [String b]);
+typedef int Bar(bool a, [String b]);
+typedef int Baz(bool a, {String b});
+typedef int Boz(bool a);
+
+class C {
+  int foo(bool a, [String b]) => null;
+  int baz(bool a, {String b}) => null;
+  int boz(bool a, {int b}) => null;
+}
+
+main() {
+  var c = new C();
+  var foo = c.foo;
+  Expect.isTrue(foo is Foo, 'foo is Foo');
+  Expect.isTrue(foo is Bar, 'foo is Bar');
+  Expect.isFalse(foo is Baz, 'foo is Baz');
+  Expect.isTrue(foo is Boz, 'foo is Boz');
+
+  var baz = c.baz;
+  Expect.isFalse(baz is Foo, 'baz is Foo');
+  Expect.isFalse(baz is Bar, 'baz is Bar');
+  Expect.isTrue(baz is Baz, 'baz is Baz');
+  Expect.isTrue(baz is Boz, 'baz is Boz');
+
+  var boz = c.boz;
+  Expect.isFalse(boz is Foo, 'boz is Foo');
+  Expect.isFalse(boz is Bar, 'boz is Bar');
+  Expect.isFalse(boz is Baz, 'boz is Baz');
+  Expect.isTrue(boz is Boz, 'boz is Boz');
+}