Generate tear-off closures dynamically.

dart/tests/compiler/dart2js_extra/mirror_invalid_field_access4_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.
 
 // Test that we cannot reflect on elements not covered by the `MirrorsUsed`
 // annotation.
 
 library test;
 
 @MirrorsUsed(targets: 'C.foo')
@@ skipping 16 matching lines @@
 main() {
   var c = inscrutable(1) == 1 ? new C() : new D();
 
   c.bar = 1;
   var local = c.bar;
 
   var mirror = reflect(c);
   Expect.equals(1, mirror.setField(const Symbol('foo'), 1).reflectee);
   Expect.equals(1, mirror.getField(const Symbol('foo')).reflectee);
   Expect.throws(() => mirror.setField(const Symbol('bar'),  2),
-                (e) => e is UnsupportedError);
+                (e) => e is NoSuchMethodError);
   Expect.throws(() => mirror.getField(const Symbol('bar')),
-                (e) => e is UnsupportedError);
+                (e) => e is NoSuchMethodError);
 }