Remove deprecated APIs.

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.
-
-import 'base64.dart';
-
-/// This class is deprecated.
-@Deprecated("Will be removed in crypto 1.0.0.")
-abstract class CryptoUtils {
-  /// This is deprecated.
-  ///
-  /// Use `hex` from `package:convert` instead.
-  static String bytesToHex(List<int> bytes) {
-    var result = new StringBuffer();
-    for (var part in bytes) {
-      result.write('${part < 16 ? '0' : ''}${part.toRadixString(16)}');
-    }
-    return result.toString();
-  }
-
-  /// This is deprecated.
-  ///
-  /// Use `BASE64` from `dart:convert` instead.
-  static String bytesToBase64(List<int> bytes,
-          {bool urlSafe: false, bool addLineSeparator: false}) =>
-      BASE64.encode(bytes,
-          urlSafe: urlSafe, addLineSeparator: addLineSeparator);
-
-  /// This is deprecated.
-  ///
-  /// Use `BASE64` from `dart:convert` instead.
-  static List<int> base64StringToBytes(String input) => BASE64.decode(input);
-}