Remove deprecated APIs.

lib/src/base64/decoder_sink.dart

-// Copyright (c) 2015, 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:convert';
-
-import 'decoder.dart';
-
-/// This is deprecated.
-///
-/// Use the `Base64Decoder` class in `dart:convert` instead.
-@Deprecated("Will be removed in crypto 1.0.0.")
-class Base64DecoderSink extends ChunkedConversionSink<String> {
-  /// The encoder used to decode each chunk.
-  final Base64Decoder _decoder = new Base64Decoder();
-
-  /// The underlying sink to which to emit the decoded strings.
-  final ChunkedConversionSink<List<int>> _outSink;
-
-  /// The as-yet-unconverted text.
-  ///
-  /// This is used to handle text stopping partway through a four-character
-  /// 32-bit chunk.
-  String _unconverted = "";
-
-  Base64DecoderSink(this._outSink);
-
-  void add(String chunk) {
-    if (chunk.isEmpty) return;
-    if (_unconverted.isNotEmpty) chunk = _unconverted + chunk;
-    chunk = chunk.replaceAll("%3D", "=");
-
-    // The decodable length is the length of the initial substring comprising
-    // full four-character 32-bit chunks. Any leftovers are handled when [add]
-    // or [close] are next called.
-    var decodableLength = chunk.length;
-    if (chunk.length > 3 && chunk.contains("%", chunk.length - 2)) {
-      decodableLength = chunk.lastIndexOf("%");
-    }
-    decodableLength -= decodableLength % 4;
-
-    _unconverted = chunk.substring(decodableLength);
-    if (decodableLength > 0) {
-      _outSink.add(_decoder.convert(chunk.substring(0, decodableLength)));
-    }
-  }
-
-  void close() {
-    if (_unconverted.isNotEmpty) _outSink.add(_decoder.convert(_unconverted));
-    _outSink.close();
-  }
-}