Enable webdriver component in test.dart

tools/testing/dart/test_runner.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("test_runner");
 
 #import("status_file_parser.dart");
 #import("test_progress.dart");
 #import("test_suite.dart");
 
@@ skipping 48 matching lines @@
         var prefixSplit = prefix.split(' ');
         var newExecutablePath = prefixSplit[0];
         for (int i = 1; i < prefixSplit.length; i++) {
           var current = prefixSplit[i];
           if (!current.isEmpty()) newArguments.add(current);
         }
         newArguments.add(executablePath);
         executablePath = newExecutablePath;
       }
       newArguments.addAll(arguments);
-      var suffixSplit = prefix.split(' ');
+      var suffixSplit = suffix.split(' ');
       suffixSplit.forEach((e) {
         if (!e.isEmpty()) newArguments.add(e);
       });
       arguments = newArguments;
     }
   }
 
   int get timeout() => configuration['timeout'];
 
   void completed() { completedHandler(this); }
@@ skipping 404 matching lines @@
           test.displayName != 'dartc/junit_tests') {
         _ensureDartcBatchRunnersStarted(test.executablePath);
         _getDartcBatchRunnerProcess().startTest(test);
       } else {
         new RunningProcess(test).start();
       }
       _numProcesses++;
     }
   }
 }