Remove deprecated string features.

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 264 matching lines @@
           var data = s.read();
           if (data != null) {
             sbuf.add(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. We have to do this the hard way as
-          // replaceAll('\0', '') does not work.
+          // 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
           // in WebDriver stack.
           for (var i = results.length; --i >= 0;) {
-            var code = results.charCodeAt(i);
+            var code = results.codeUnitAt(i);
             if (code != 0) {
-              results = results.substring(0, i+1);
+              results = results.substring(0, i + 1);
               break;
             }
           }
           if (successCodes.indexOf(r.statusCode) < 0) {
             throw 'Unexpected response ${r.statusCode}';
           }
           if (status == 0 && results.length > 0) {
             // 4xx responses send plain text; others send JSON.
             if (r.statusCode < 400) {
               results = json.parse(results);
@@ skipping 1052 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 });
 }