Remove Sink and move CollectionSink to async.

sdk/lib/core/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.core;
-/**
- * An interface for an object that can receive a sequence of values.
- */
-abstract class Sink<T> {
-  /** Write a value to the sink. */
-  add(T value);
-  /** Tell the sink that no further values will be written. */
-  void close();
-}
-
-// ----------------------------------------------------------------------
-// Collections/Sink interoperability
-// ----------------------------------------------------------------------
-
-typedef void _CollectionSinkCallback<T>(Collection<T> collection);
-
-/** Sink that stores incoming data in a collection. */
-class CollectionSink<T> implements Sink<T> {
-  final Collection<T> collection;
-  final _CollectionSinkCallback<T> callback;
-  bool _isClosed = false;
-
-  /**
-   * Create a sink that stores incoming values in a collection.
-   *
-   * The [collection] is the collection to add the values to.
-   *
-   * If [callback] is provided, then it's called with the collection as arugment
-   * when the sink's [close] method is called.
-   */
-  CollectionSink(this.collection, [void callback(Collection<T> collection)])
-      : this.callback = callback;
-
-  add(T value) {
-    if (_isClosed) throw new StateError("Adding to closed sink");
-    collection.add(value);
-  }
-
-  void close() {
-    if (_isClosed) throw new StateError("Closing closed sink");
-    _isClosed = true;
-    if (callback != null) callback(collection);
-  }
-}