pkg/docgen: moved model classes into minilibs

pkg/docgen/lib/src/exports/mirrors_util.dart

Index: pkg/docgen/lib/src/exports/mirrors_util.dart
diff --git a/runtime/vm/stub_code_arm64_test.cc b/pkg/docgen/lib/src/exports/mirrors_util.dart
similarity index 62%
copy from runtime/vm/stub_code_arm64_test.cc
copy to pkg/docgen/lib/src/exports/mirrors_util.dart
index 7c2fe8f24e2c2b105216c145ac790527ca4c0dba..2479fbe304ee551b1ef3d023356bd5d1319f96a4 100644
--- a/runtime/vm/stub_code_arm64_test.cc
+++ b/pkg/docgen/lib/src/exports/mirrors_util.dart
@@ -2,9 +2,6 @@
 // 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.
 
-#include "vm/globals.h"
-#if defined(TARGET_ARCH_ARM64)
+library docgen.exports.mirrors_util;
 
-// TODO(zra): Port these tests.
-
-#endif  // defined TARGET_ARCH_ARM64
+export '../../../../../sdk/lib/_internal/compiler/implementation/mirrors/mirrors_util.dart';