[flutter_tools] dont use SETLOCAL ENABLEDELAYEDEXPANSION unecessarily (#85288)

bin/dart.bat

@@ -11,8 +11,6 @@ REM work across all platforms!
 REM
 REM --------------------------------------------------------------------------
 
-SETLOCAL ENABLEDELAYEDEXPANSION
-
 FOR %%i IN ("%~dp0..") DO SET FLUTTER_ROOT=%%~fi
 
 REM Include shared scripts in shared.bat

bin/flutter.bat

@@ -11,8 +11,6 @@ REM work across all platforms!
 REM
 REM --------------------------------------------------------------------------
 
-SETLOCAL ENABLEDELAYEDEXPANSION
-
 FOR %%i IN ("%~dp0..") DO SET FLUTTER_ROOT=%%~fi
 
 REM If available, add location of bundled mingit to PATH

packages/flutter_tools/test/integration.shard/variable_expansion_windows.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Not a test file, invoked by `variable_expansion_windows_test.dart`.
+void main(List<String> args) {
+  print('args: $args');
+}

packages/flutter_tools/test/integration.shard/variable_expansion_windows_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.8
+import 'package:flutter_tools/src/base/io.dart';
+
+import '../src/common.dart';
+import 'test_utils.dart';
+
+void main() {
+  // Regression test for https://github.com/flutter/flutter/issues/84270 .
+  testWithoutContext('dart command will expand variables on windows', () async {
+    final ProcessResult result = await processManager.run(<String>[
+      fileSystem.path.join(getFlutterRoot(), 'bin', 'dart'),
+      fileSystem.path.join(getFlutterRoot(), 'packages', 'flutter_tools', 'test', 'integration.shard', 'variable_expansion_windows.dart'),
+      '"^(?!Golden).+"',
+    ]);
+    expect(result.stdout, contains('args: ["(?!Golden).+"]'));
+  }, skip: !platform.isWindows);
+}