fixes #27385, implement virtual fields in DDC

tests/language_strong/override_inheritance_field_test.dart

Index: tests/language_strong/override_inheritance_field_test.dart
diff --git a/tests/language_strong/override_inheritance_field_test.dart b/tests/language_strong/override_inheritance_field_test.dart
index 7e2b28bff302a7b05d3e899f0d018dafbb3d7cbf..dbb17fa8ec01cd08171b2a620b832b758aa4dc0a 100644
--- a/tests/language_strong/override_inheritance_field_test.dart
+++ b/tests/language_strong/override_inheritance_field_test.dart
@@ -2,6 +2,8 @@
 // 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.
 
+import "package:meta/meta.dart" show virtual;
+
 class A {
   get getter1 => null; /// 01: ok
   num get getter2 => null; /// 02: ok
@@ -24,12 +26,12 @@ class A {
   set setter10(int _) => null; /// 30: static type warning
   set setter11(int _) => null; /// 31: static type warning
 
-  int field1; /// 41: ok
+  @virtual int field1; /// 41: ok
   num field2; /// 42: ok
   int field3; /// 43: ok
   int field4; /// 44: static type warning
   int field5; /// 45: ok
-  num field6; /// 46: ok
+  @virtual num field6; /// 46: ok
   num field7; /// 47: static type warning
   num get field8 => null; /// 48: static type warning
   num field9; /// 49: ok