Fix hints reported by analyzer.

pkg/compiler/lib/src/hash/sha1.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.
 
 /**
  * SHA-1.
  * Ripped from package:crypto.
  */
 library sha1;
 
@@ skipping 60 matching lines @@
 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.
 abstract class _HashBase implements Hash {
   final int _chunkSizeInWords;
-  final int _digestSizeInWords;
   final bool _bigEndianWords;
   final List<int> _currentChunk;
   final List<int> _h;
   int _lengthInBytes = 0;
   List<int> _pendingData;
   bool _digestCalled = false;
 
   _HashBase(
       int chunkSizeInWords, int digestSizeInWords, bool this._bigEndianWords)
       : _pendingData = [],
         _currentChunk = new List(chunkSizeInWords),
         _h = new List(digestSizeInWords),
-        _chunkSizeInWords = chunkSizeInWords,
-        _digestSizeInWords = digestSizeInWords;
+        _chunkSizeInWords = chunkSizeInWords;
 
   // Update the hasher with more data.
   void add(List<int> data) {
     if (_digestCalled) {
       throw new StateError(
           'Hash update method called after digest was retrieved');
     }
     _lengthInBytes += data.length;
     _pendingData.addAll(data);
     _iterate();
@@ skipping 255 matching lines @@
       int y = bytes[i + 1];
       out[j++] = lookup.codeUnitAt(x >> 2);
       out[j++] = lookup.codeUnitAt(((x << 4) | (y >> 4)) & 0x3F);
       out[j++] = lookup.codeUnitAt((y << 2) & 0x3F);
       out[j++] = PAD;
     }
 
     return new String.fromCharCodes(out);
   }
 }