fixes #27385, implement virtual fields in DDC

tests/lib_strong/mirrors/instance_members_with_override_test.dart

Index: tests/lib_strong/mirrors/instance_members_with_override_test.dart
diff --git a/tests/lib_strong/mirrors/instance_members_with_override_test.dart b/tests/lib_strong/mirrors/instance_members_with_override_test.dart
index 6c75085a8fcb1f73800a438dcfe3b822bfdc670a..17c0b35c9fef53ce34079f5f18e8408393fbb4d6 100644
--- a/tests/lib_strong/mirrors/instance_members_with_override_test.dart
+++ b/tests/lib_strong/mirrors/instance_members_with_override_test.dart
@@ -6,10 +6,11 @@ library test.instance_members_with_override;
 
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
+import 'package:meta/meta.dart' show virtual;
 
 class S {
-  var field;
-  final finalField = 0;
+  @virtual var field;
+  @virtual final finalField = 0;
   method() {}
   get getter {}
   set setter(x) {}