trim() does not remove the trailing null characters.

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:async';
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:uri';
@@ skipping 267 matching lines @@
         if (params != null) {
           var body = json.stringify(params);
           req.write(body);
         }
         req.close().then((rsp) {
           List<int> body = new List<int>();
           rsp.listen(body.addAll, onDone: () {
             var value = null;
             // 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 with trim().
+            // 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.
-            results = new String.fromCharCodes(body).trim();
+            results = new String.fromCharCodes(body)
+                .replaceAll(new RegExp('\u{0}*\$'), '');
             if (!successCodes.contains(rsp.statusCode)) {
               _failRequest(completer, 
                   'Unexpected response ${rsp.statusCode}; $results');
               completer = null;
               return;
             }
             if (status == 0 && results.length > 0) {
               // 4xx responses send plain text; others send JSON.
               if (rsp.statusCode < 400) {
                 results = json.parse(results);
@@ skipping 572 matching lines @@
   Future<String> getElementWithFocus() => _post('element/active');
 
   /**
    * Search for an element on the page, starting from element with id [id].
    * The located element will be returned as WebElement JSON objects. See
    * [findElement] for the locator strategies that each server supports.
    *
    * Potential Errors: NoSuchWindow, XPathLookupError.
    */
   Future<String>
-      findElementFromId(String id, String strategy, String searchValue) {
-    _post('element/$id/element', { 'using': strategy, 'value' : searchValue });
-  }
+      findElementFromId(String id, String strategy, String searchValue) =>
+          _post('element/$id/element',
+              { 'using': strategy, 'value' : searchValue });
 
   /**
    * Search for multiple elements on the page, starting from the element with
    * id [id].The located elements will be returned as WebElement JSON objects.
    * See [findElement] for the locator strategies that each server supports.
    * Elements are be returned in the order located in the DOM.
    *
    * Potential Errors: NoSuchWindow, XPathLookupError.
    */
   Future<List<String>>
       findElementsFromId(String id, String strategy, String searchValue) =>
           _post('element/$id/elements',
-              params: { 'using': strategy, 'value' : searchValue });
+              { 'using': strategy, 'value' : searchValue });
 
   /**
    * Click on an element specified by [id].
    *
    * Potential Errors: NoSuchWindow, StaleElementReference, ElementNotVisible
    * (if the referenced element is not visible on the page, either hidden
    * by CSS, or has 0-width or 0-height).
    */
   Future clickElement(String id) => _post('element/$id/click');
 
@@ skipping 549 matching lines @@
    *
    * 'timestamp' (int) - The timestamp of the entry.
    * 'level' (String) - The log level of the entry, for example, "INFO".
    * 'message' (String) - The log message.
    *
    * This works with Firefox but Chrome returns a 500 response due to a 
    * bad cast.
    */
   Future<List<Map>> getLogs(String type) => _post('log', { 'type': type });
 }