Close underlying Hash sinks.

lib/src/hash_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.
 
 import 'dart:typed_data';
 
 import 'package:typed_data/typed_data.dart';
 
 import 'digest.dart';
 import 'utils.dart';
@@ skipping 52 matching lines @@
   }
 
   void close() {
     if (_isClosed) return;
     _isClosed = true;
 
     _finalizeData();
     _iterate();
     assert(_pendingData.isEmpty);
     _sink.add(new Digest(_byteDigest()));
+    _sink.close();
   }
 
   Uint8List _byteDigest() {
     if (_endian == Endianness.HOST_ENDIAN) return digest.buffer.asUint8List();
 
     var byteDigest = new Uint8List(digest.lengthInBytes);
     var byteData = byteDigest.buffer.asByteData();
     for (var i = 0; i < digest.length; i++) {
       byteData.setUint32(i * bytesPerWord, digest[i]);
     }
@@ skipping 58 matching lines @@
     } else {
       byteData.setUint32(offset, lowBits, _endian);
       byteData.setUint32(offset + bytesPerWord, highBits, _endian);
     }
   }
 
   /// Rounds [val] up to the next multiple of [n], as long as [n] is a power of
   /// two.
   int _roundUp(int val, int n) => (val + n - 1) & -n;
 }