Language tests updated to use const instead of final.

tests/language/compile_time_constant_c_test.dart

Index: tests/language/compile_time_constant_c_test.dart
diff --git a/tests/language/compile_time_constant_c_test.dart b/tests/language/compile_time_constant_c_test.dart
index 452b11c68f85e5928f47f638875bfc9c771118f5..b1bd81a62d30ad958f16c31cef637154ad210e1c 100644
--- a/tests/language/compile_time_constant_c_test.dart
+++ b/tests/language/compile_time_constant_c_test.dart
@@ -2,10 +2,10 @@
 // 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.
 
-final m1 = const {
+const m1 = const {
   499: 400 + 99  /// 01: compile-time error
 };
-final m2 = const {
+const m2 = const {
   "foo" + "bar": 42  /// 02: compile-time error
 };