Language tests updated to use const instead of final.

tests/language/compile_time_constant_k_test.dart

Index: tests/language/compile_time_constant_k_test.dart
diff --git a/tests/language/compile_time_constant_k_test.dart b/tests/language/compile_time_constant_k_test.dart
index 7b1857ede57cbeec4c850da84ab8bfc9a3a6c559..50ebcc47fd7a72bf88bd9eeb9f6481228fde6c04 100644
--- a/tests/language/compile_time_constant_k_test.dart
+++ b/tests/language/compile_time_constant_k_test.dart
@@ -9,9 +9,9 @@ final z = const { '__proto__': 496,
                   '__proto__': 498,
                   '__proto__': 499 };
 
-final x2 = const { 'a': 4 };
-final y2 = const { 'a': 14, 'b': 13 };
-final z2 = const { '__proto__': 499 };
+const x2 = const { 'a': 4 };
+const y2 = const { 'a': 14, 'b': 13 };
+const z2 = const { '__proto__': 499 };
 
 main() {
   Expect.identical(x2, x);