[wildcard-variables] Add tests for const behaviour.

Missing a few cases for interactions between wildcard variables and const.

Bug: #55652
Change-Id: I4ae1ca0041b5b8ca3c24ab866bd9d8e19832ef2e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/382963
Commit-Queue: Kallen Tu <[email protected]>
Reviewed-by: Bob Nystrom <[email protected]>

Author: kallentu

tests/language/wildcard_variables/multiple/local_declaration_local_test.dart

@@ -22,4 +22,6 @@ void main() {
 
   late final int _;
   late final int _ = 2;
+
+  const int _ = 2;
 }

tests/language/wildcard_variables/non_binding/top_level_const_test.dart

@@ -0,0 +1,21 @@
+// Copyright (c) 2024, 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.
+
+// Tests that top-level const variables are still binding.
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+import 'package:expect/expect.dart';
+
+const _ = 100;
+
+void main() {
+  var _ = 1;
+  int _ = 2;
+  final _ = 3;
+  late int _ = 4;
+  const int _ = 5;
+
+  Expect.equals(100, _);
+}