remove generated_sdk from checked in code

test/generated_sdk/lib/core/sink.dart

-// 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.
-
-part of dart.core;
-
-/**
- * A generic destination for data.
- *
- * Multiple data values can be put into a sink, and when no more data is
- * available, the sink should be closed.
- *
- * This is a generic interface that other data receivers can implement.
- */
-abstract class Sink<T> {
-  /**
-   * Put the data into the sink.
-   *
-   * Must not be called after a call to [close].
-   */
-  void add(T data);
-
-  /**
-   * Tell the sink that no further data will be added.
-   *
-   * Calling this method more than once is allowed, but does nothing.
-   *
-   * The [add] method must not be called after this method.
-   */
-  void close();
-}