Use growable lists.

dart/tests/lib/mirrors/mirrors_used_merge_test.dart

Index: dart/tests/lib/mirrors/mirrors_used_merge_test.dart
diff --git a/dart/tests/compiler/dart2js_extra/mirrors_used_native_test.dart b/dart/tests/lib/mirrors/mirrors_used_merge_test.dart
similarity index 50%
copy from dart/tests/compiler/dart2js_extra/mirrors_used_native_test.dart
copy to dart/tests/lib/mirrors/mirrors_used_merge_test.dart
index a546682f0c82ad8145e358df464f8ea016b85000..534c5e71dd2ad7bd495a54afa24d99001495c707 100644
--- a/dart/tests/compiler/dart2js_extra/mirrors_used_native_test.dart
+++ b/dart/tests/lib/mirrors/mirrors_used_merge_test.dart
@@ -2,13 +2,14 @@
 // 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.
 
-@MirrorsUsed(targets: 'List')
-import 'dart:mirrors';
+/// Test that two MirrorsUsed annotations can be merged with out crashing
+/// dart2js.
 
-import 'package:expect/expect.dart';
+@MirrorsUsed(symbols: const ['foo'])
+@MirrorsUsed(symbols: const ['bar'])
+import 'dart:mirrors';
 
 main() {
-  Expect.equals(3, reflect([1, 2, 3]).getField(#length).reflectee);
-  Expect.throws(() => reflect({"hest": 42}).getField(#length),
-                (e) => e is UnsupportedError);
+  // Do nothing, just make sure that merging the annotations doesn't crash
+  // dart2js.
 }