pkg/docgen: moved model classes into minilibs

pkg/docgen/lib/src/exports/dart2js_mirrors.dart

Index: pkg/docgen/lib/src/exports/dart2js_mirrors.dart
diff --git a/runtime/vm/stub_code_arm64_test.cc b/pkg/docgen/lib/src/exports/dart2js_mirrors.dart
similarity index 61%
copy from runtime/vm/stub_code_arm64_test.cc
copy to pkg/docgen/lib/src/exports/dart2js_mirrors.dart
index 7c2fe8f24e2c2b105216c145ac790527ca4c0dba..894dd51878e72a80e85c60756f4022d64316ab38 100644
--- a/runtime/vm/stub_code_arm64_test.cc
+++ b/pkg/docgen/lib/src/exports/dart2js_mirrors.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.dart2js_mirrors;
 
-// TODO(zra): Port these tests.
-
-#endif  // defined TARGET_ARCH_ARM64
+export '../../../../../sdk/lib/_internal/compiler/implementation/mirrors/dart2js_mirrors.dart';