Add test for checked setters of generic types.

tests/language/checked_setter2_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 implicit setters in checked mode do a type check.
+// Test that implicit setters in checked mode do a type check generic types.
 
 import "package:expect/expect.dart";
 
 class A {
-  C c;
+  C<int> c;
 }
 
 class B extends A {
 }
 
-class C {
+class C<T> {
 }
 
 var array = [new B()];
 
 main() {
   array[0].c = new C();
   bool inCheckedMode = false;
   try {
     String a = 42;
   } catch (e) {
     inCheckedMode = true;
   }
   if (inCheckedMode) {
-    Expect.throws(() => array[0].c = new B(), (e) => e is TypeError);
+    Expect.throws(() => array[0].c = new C<bool>(), (e) => e is TypeError);
   }
-}
+}