Fix result type checking of factory constructors of generic classes in VM.

tests/language/factory_redirection_test.dart

Index: tests/language/factory_redirection_test.dart
===================================================================
--- tests/language/factory_redirection_test.dart	(revision 14760)
+++ tests/language/factory_redirection_test.dart	(working copy)
@@ -62,7 +62,7 @@
   new C.test07<int, int>(0);  /// 07: continued
   Expect.isTrue(new A<List>() is A<List>);
   Expect.isTrue(new A<bool>.constant(true).x);
-  Expect.isTrue(new A<List>.factory() is B<Set>);
+  Expect.isTrue(new A<Set>.factory() is B<Set>);
   Expect.isTrue(new B<List>.A() is A<List>);
   Expect.isTrue(new B<bool>.A_constant(true).x);
   Expect.isTrue(new B<List>.A_factory() is B<Set>);