Deprecate Collection class.

sdk/lib/async/collection_sink.dart

 // Copyright (c) 2012, 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.
 
 part of dart.async;
 
 typedef void _CollectionSinkCallback<T>(Collection<T> collection);
 typedef void _CollectionSinkErrorCallback(AsyncError error);
 
-/** EventSink that stores incoming data in a collection. */
+/**
+ * EventSink that stores incoming data in a collection.
+ *
+ * *Deprecated*.
+ */
 class CollectionSink<T> extends StreamSink<T> {
   // TODO(8997): Implement EventSink instead.
   final Collection<T> collection;
   final _CollectionSinkCallback<T> _callback;
   final _CollectionSinkErrorCallback _errorCallback;
   bool _isClosed = false;
 
   /**
    * Create a sink that stores incoming values in a collection.
    *
@@ skipping 17 matching lines @@
     if (_isClosed) throw new StateError("Adding error to closed sink");
     if (_errorCallback != null) _errorCallback(error);
   }
 
   void close() {
     if (_isClosed) throw new StateError("Closing closed sink");
     _isClosed = true;
     if (_callback != null) _callback(collection);
   }
 }