Make interfaces into abstract classes in 'dart:crypto'.

sdk/lib/crypto/hash_utils.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.
 
 // Constants.
 const _MASK_8 = 0xff;
 const _MASK_32 = 0xffffffff;
 const _BITS_PER_BYTE = 8;
 const _BYTES_PER_WORD = 4;
 
 // Helper functions used by more than one hasher.
 
 // Rotate left limiting to unsigned 32-bit values.
 int _rotl32(int val, int shift) {
   var mod_shift = shift & 31;
   return ((val << mod_shift) & _MASK_32) |
       ((val & _MASK_32) >> (32 - mod_shift));
 }
 
 // Base class encapsulating common behavior for cryptographic hash
 // functions.
-class _HashBase implements Hash {
+abstract class _HashBase implements Hash {
   _HashBase(int this._chunkSizeInWords,
             int this._digestSizeInWords,
             bool this._bigEndianWords)
       : _pendingData = [] {
     _currentChunk = new List(_chunkSizeInWords);
     _h = new List(_digestSizeInWords);
   }
 
   // Update the hasher with more data.
   _HashBase update(List<int> data) {
@@ skipping 18 matching lines @@
     assert(_pendingData.length == 0);
     return _resultAsBytes();
   }
 
   // Returns the block size of the hash in bytes.
   int get blockSize {
     return _chunkSizeInWords * _BYTES_PER_WORD;
   }
 
   // Create a fresh instance of this Hash.
-  abstract newInstance();
+  newInstance();
 
   // One round of the hash computation.
-  abstract _updateHash(List<int> m);
+  _updateHash(List<int> m);
 
   // Helper methods.
   _add32(x, y) => (x + y) & _MASK_32;
   _roundUp(val, n) => (val + n - 1) & -n;
 
   // Compute the final result as a list of bytes from the hash words.
   _resultAsBytes() {
     var result = [];
     for (var i = 0; i < _h.length; i++) {
       result.addAll(_wordToBytes(_h[i]));
@@ skipping 70 matching lines @@
   // Hasher state.
   final int _chunkSizeInWords;
   final int _digestSizeInWords;
   final bool _bigEndianWords;
   int _lengthInBytes = 0;
   List<int> _pendingData;
   List<int> _currentChunk;
   List<int> _h;
   bool _digestCalled = false;
 }