Move some core classes to collection library.

tests/corelib/collection_test.dart

Index: tests/corelib/collection_test.dart
diff --git a/tests/corelib/collection_test.dart b/tests/corelib/collection_test.dart
index 86d9e03d3f5a95bc0acf7477af85b7d5be80ddac..202b4bbc715769f94a51c924b5bdb6888f067d10 100644
--- a/tests/corelib/collection_test.dart
+++ b/tests/corelib/collection_test.dart
@@ -2,6 +2,10 @@
 // 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 collection_test;
+
+import 'dart:collection' show Queue;
+
 class CollectionTest {
   CollectionTest(Collection collection) {
     testReduce(collection);