trim() does not remove the trailing null characters.

pkg/webdriver/lib/webdriver.dart

Index: pkg/webdriver/lib/webdriver.dart
diff --git a/pkg/webdriver/lib/webdriver.dart b/pkg/webdriver/lib/webdriver.dart
index 724332d959d10ee7496c866a891ea2db91301d4f..7cfabe607e27abde81d073a880e1739ee45cb064 100644
--- a/pkg/webdriver/lib/webdriver.dart
+++ b/pkg/webdriver/lib/webdriver.dart
@@ -285,11 +285,12 @@ class WebDriverBase {
             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}; $results');
@@ -882,9 +883,9 @@ class WebDriverSession extends WebDriverBase {
    * Potential Errors: NoSuchWindow, XPathLookupError.
    */
   Future<String>
-      findElementFromId(String id, String strategy, String searchValue) {
-    _post('element/$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
@@ -897,7 +898,7 @@ class WebDriverSession extends WebDriverBase {
   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].