Remove deprecated StringBuffer.add, addAll and addCharCode.

pkg/webdriver/lib/webdriver.dart

 // Copyright (c) 2011, 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.
 
 library webdriver;
 
 import 'dart:json' as json;
 import 'dart:uri';
 import 'dart:io';
 
@@ skipping 250 matching lines @@
           completer = null;
         }
       };
       connection.followRedirects = false;
       connection.onResponse = (r) {
         StringInputStream s = new StringInputStream(r.inputStream);
         StringBuffer sbuf = new StringBuffer();
         s.onData = () {
           var data = s.read();
           if (data != null) {
-            sbuf.add(data);
+            sbuf.write(data);
           }
         };
         s.onClosed = () {
           var value = null;
           results  = sbuf.toString().trim();
           // For some reason we get a bunch of NULs on the end
           // of the text and the json.parse blows up on these, so
           // strip them.
           // These NULs can be seen in the TCP packet, so it is not
           // an issue with character encoding; it seems to be a bug
@@ skipping 1067 matching lines @@
    * Get the log for a given log type. Log buffer is reset after each request.
    * Each log entry is a [Map] with these fields:
    *
    * 'timestamp' (int) - The timestamp of the entry.
    * 'level' (String) - The log level of the entry, for example, "INFO".
    * 'message' (String) - The log message.
    */
   Future<List<Map>> getLogs(String type) =>
       _post('log', params: { 'type': type });
 }