Revert two Kernel changes that were causing test failures.

tests/language_2/assign_to_type_test.dart

Index: tests/language_2/assign_to_type_test.dart
diff --git a/tests/language_2/assign_to_type_test.dart b/tests/language_2/assign_to_type_test.dart
deleted file mode 100644
index c8e49324d684999989ba5cd6d394e188fa815aa5..0000000000000000000000000000000000000000
--- a/tests/language_2/assign_to_type_test.dart
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright (c) 2015, 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.
-
-// Verify that an attempt to assign to a class, enum, typedef, or type
-// parameter produces a compile error.
-
-class C<T> {
-  f() {
-    T = null; //# 01: compile-time error
-  }
-}
-
-class D {}
-
-enum E { e0 }
-
-typedef void F();
-
-main() {
-  new C<D>().f();
-  D = null; //# 02: compile-time error
-  E = null; //# 03: compile-time error
-  F = null; //# 04: compile-time error
-}