Remove deprecated string features.

sdk/lib/io/websocket_impl.dart

 // Copyright (c) 2013, 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.io;
 
 const String _webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
 class _WebSocketMessageType {
   static const int NONE = 0;
@@ skipping 576 matching lines @@
       response.outputStream.close();
       return;
     }
 
     // Send the upgrade response.
     response.statusCode = HttpStatus.SWITCHING_PROTOCOLS;
     response.headers.add(HttpHeaders.CONNECTION, "Upgrade");
     response.headers.add(HttpHeaders.UPGRADE, "websocket");
     String key = request.headers.value("Sec-WebSocket-Key");
     SHA1 sha1 = new SHA1();
-    sha1.add("$key$_webSocketGUID".charCodes);
+    sha1.add("$key$_webSocketGUID".codeUnits);
     String accept = _Base64._encode(sha1.close());
     response.headers.add("Sec-WebSocket-Accept", accept);
     response.contentLength = 0;
 
     // Upgrade the connection and get the underlying socket.
     WebSocketConnection conn =
         new _WebSocketConnection(response.detachSocket());
     if (_onOpen != null) _onOpen(conn);
   }
 
@@ skipping 127 matching lines @@
     if (!isUpgrade) return false;
     String upgrade = response.headers.value(HttpHeaders.UPGRADE);
     if (upgrade == null || upgrade.toLowerCase() != "websocket") {
       return false;
     }
     String accept = response.headers.value("Sec-WebSocket-Accept");
     if (accept == null) {
       return false;
     }
     SHA1 sha1 = new SHA1();
-    sha1.add("$_nonce$_webSocketGUID".charCodes);
+    sha1.add("$_nonce$_webSocketGUID".codeUnits);
     List<int> expectedAccept = sha1.close();
     List<int> receivedAccept = _Base64._decode(accept);
     if (expectedAccept.length != receivedAccept.length) return false;
     for (int i = 0; i < expectedAccept.length; i++) {
       if (expectedAccept[i] != receivedAccept[i]) return false;
     }
     return true;
   }
 
   Function _onRequest;
@@ skipping 107 matching lines @@
 
 class _WebSocketCloseEvent implements CloseEvent {
   _WebSocketCloseEvent(this._wasClean, this._code, this._reason);
   bool get wasClean => _wasClean;
   int get code => _code;
   String get reason => _reason;
   bool _wasClean;
   int _code;
   String _reason;
 }