Handle metadata with type literals or qualified identifiers.

tests/lib/mirrors/metadata_allowed_values_import.dart

Index: tests/lib/mirrors/metadata_allowed_values_import.dart
diff --git a/runtime/lib/symbol_patch.dart b/tests/lib/mirrors/metadata_allowed_values_import.dart
similarity index 70%
copy from runtime/lib/symbol_patch.dart
copy to tests/lib/mirrors/metadata_allowed_values_import.dart
index be09eaef8c985eac7d3c929c2d0665a53378a4a3..67df4e21ab29a23c7cf0b83f32a8b6c8a6dea776 100644
--- a/runtime/lib/symbol_patch.dart
+++ b/tests/lib/mirrors/metadata_allowed_values_import.dart
@@ -2,7 +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.
 
-patch class Symbol {
-  /* patch */ const Symbol(String name)
-      : this._name = name;
+class Imported {
+  const Imported();
+  const Imported.named();
+  static const CONSTANT = 0;
 }