Update test for assignment to final variables

tests/language/final_var_negative_test.dart

Index: tests/language/final_var_negative_test.dart
diff --git a/tests/language/final_var_negative_test.dart b/tests/language/final_var_negative_test.dart
deleted file mode 100644
index 62d4e536f6bf1a53d420d38489c66584520382b7..0000000000000000000000000000000000000000
--- a/tests/language/final_var_negative_test.dart
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright (c) 2011, 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.
-// Disallow re-assignment of a final local variable.
-
-main() {
-  final x = 1;
-  x = 2;  // <- reassignment not allowed.
-  return x;
-}