Make base64 decoding available in dart:crypto

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 fbae2d3e2a5b1d24aed82127e048998318689994..cf2eb597b3320676b9d165238789d24d1bae2d05 100644
--- a/pkg/webdriver/lib/webdriver.dart
+++ b/pkg/webdriver/lib/webdriver.dart
@@ -5,12 +5,11 @@
 library webdriver;
 
 import 'dart:async';
+import 'dart:crypto';
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:uri';
 
-part 'src/base64decoder.dart';
-
 /**
  * WebDriver bindings for Dart.
  *
@@ -663,7 +662,7 @@ class WebDriverSession extends WebDriverBase {
   Future<List<int>> getScreenshot([fname]) {
     var completer = new Completer();
     return _get('screenshot', completer, (r, v) {
-      var image = Base64Decoder.decode(v);
+      var image = CryptoUtils.base64StringToBytes(v);
       if (fname != null) {
         writeBytesToFile(fname, image);
       }