Update or delete language tests using obsolete interfaces or default factory

tests/language/generic_syntax_test.dart

Index: tests/language/generic_syntax_test.dart
===================================================================
--- tests/language/generic_syntax_test.dart	(revision 15648)
+++ tests/language/generic_syntax_test.dart	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2012, 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.
 
@@ -38,7 +38,7 @@
   }
 }
 
-interface A<B, C, D, E, F> {
+abstract class A<B, C, D, E, F> {
 }
 
 main() {