Only use dartc batch processing for the dartc component.

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 386 matching lines @@
       if (_verbose) print(test.commandLine);
       _progress.start(test);
       Function oldCallback = test.completedHandler;
       Function wrapper = (TestCase test_arg) {
         _numProcesses--;
         _progress.done(test_arg);
         _tryRunTest();
         oldCallback(test_arg);
       };
       test.completedHandler = wrapper;
-      if (test.executablePath.contains('compiler')) {
+      if (test.configuration['component'] == 'dartc') {
         _ensureDartcBatchRunnersStarted(test.executablePath);
         _getDartcBatchRunnerProcess().startTest(test);
       } else {
         new RunningProcess(test).start();
       }
       _numProcesses++;
     }
   }
 }