Fix for issue 27567 (inconsistent handling of invalid -D options

tests/standalone/env_test.dart

Index: tests/standalone/env_test.dart
diff --git a/pkg/dev_compiler/test/codegen/language/generic_async_test.dart b/tests/standalone/env_test.dart
similarity index 65%
copy from pkg/dev_compiler/test/codegen/language/generic_async_test.dart
copy to tests/standalone/env_test.dart
index b55df668ac3e4dd7ac923573f82dfdfa7f76cc35..6280f60987dca276d14239e8c5cd4115b45937b3 100644
--- a/pkg/dev_compiler/test/codegen/language/generic_async_test.dart
+++ b/tests/standalone/env_test.dart
@@ -1,13 +1,10 @@
 // Copyright (c) 2016, 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.
+// SharedOptions=-Dvar -D -D=var -Dvar=invalid -Dvar=valid -Dvar
 
 import "package:expect/expect.dart";
 
-import 'dart:async';
-
-Future/*<T>*/ foo/*<T>*/(/*=T*/ x) async => x;
-
-main() async {
-  Expect.equals(1, await foo/*<int>*/(1));
+main() {
+  Expect.equals('valid', const String.fromEnvironment('var'));
 }