Remove library dart:crypto

pkg/crypto/lib/src/crypto_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.
 
 part of dart.crypto;
 
 abstract class _CryptoUtils {
   static String bytesToHex(List<int> bytes) {
     var result = new StringBuffer();
     for (var part in bytes) {
@@ skipping 141 matching lines @@
       out[o++] = x >> 16;
       if (o < outputLen) {
         out[o++] = (x >> 8) & 0xFF;
         if (o < outputLen) out[o++] = x & 0xFF;
       }
     }
     return out;
   }
 
 }