Language tests updated to use const instead of final.

tests/language/compile_time_constant_d_test.dart

Index: tests/language/compile_time_constant_d_test.dart
diff --git a/tests/language/compile_time_constant_d_test.dart b/tests/language/compile_time_constant_d_test.dart
index 9a3ea68e64a0f4f0c61c82d00f6dd1f65e71aef8..6695fbeb03b84163d72fee7d164e11bf04d90526 100644
--- a/tests/language/compile_time_constant_d_test.dart
+++ b/tests/language/compile_time_constant_d_test.dart
@@ -15,9 +15,9 @@ class A {
   toString() => "A $x $y $z $t";
 }
 
-final a1 = const A(99, 100);
-final a2 = const A.named(99, 100);
-final a3 = const A.named2(1, 2, 3, 4);
+const a1 = const A(99, 100);
+const a2 = const A.named(99, 100);
+const a3 = const A.named2(1, 2, 3, 4);
 
 main() {
   Expect.equals(3, a1.x);