Create associated packages for the dart:collection and dart:async libs.

pkg/collection/lib/collection.dart

Index: pkg/collection/lib/collection.dart
diff --git a/pkg/collection_helpers/lib/all.dart b/pkg/collection/lib/collection.dart
similarity index 86%
copy from pkg/collection_helpers/lib/all.dart
copy to pkg/collection/lib/collection.dart
index 3658cf1a4b8ba2f2231db06b23fffb0e402c62c0..a6f192d8057e622eaf945f3e53fe12176ae51cae 100644
--- a/pkg/collection_helpers/lib/all.dart
+++ b/pkg/collection/lib/collection.dart
@@ -10,13 +10,13 @@
  * - `algorithms.dart`: Algorithms that work on lists (shuffle, binary search
  *                      and various sorting algorithms).
  * - `equality.dart`: Different notions of equality of collections.
- * - `typed_buffers.dart`: Growable typed data lists.
+ * - `iterable_zip.dart`: Combining multiple iterables into one.
  * - `wrappers.dart`: Wrapper classes that delegate to a collection object.
  *                    Includes unmodifiable views of collections.
  */
-library dart.collection_helper;
+library dart.pkg.collection;
 
 export "algorithms.dart";
 export "equality.dart";
-export "typed_buffers.dart";
+export "iterable_zip.dart";
 export "wrappers.dart";