Added back helper file accidentally deleted during test block 219 migration.

tests/lib/mirrors/deferred_mirrors_metatarget_lib.dart

Index: tests/lib/mirrors/deferred_mirrors_metatarget_lib.dart
diff --git a/tests/lib/mirrors/deferred_mirrors_metatarget_lib.dart b/tests/lib/mirrors/deferred_mirrors_metatarget_lib.dart
deleted file mode 100644
index 1c2ec2f0baaa6fed8536fe342b0f030d107eaee5..0000000000000000000000000000000000000000
--- a/tests/lib/mirrors/deferred_mirrors_metatarget_lib.dart
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
-// 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.
-
-library lib;
-
-@MirrorsUsed(metaTargets: "MetaTarget")
-import "dart:mirrors";
-
-class MetaTarget {
-  const MetaTarget();
-}
-
-@MetaTarget()
-class A {
-  String toString() => "A";
-}
-
-String foo() {
-  ClassMirror a = currentMirrorSystem().findLibrary(#lib).declarations[#A];
-  return a.newInstance(const Symbol(""), []).invoke(#toString, []).reflectee;
-}