Reduce test.dart memory usage.

tools/test.dart

 #!/usr/bin/env dart
 // Copyright (c) 2013, 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.
 
 /**
  * This file is the entrypoint of the dart test suite.  This suite is used
  * to test:
  *
  *     1. the dart vm
@@ skipping 245 matching lines @@
     eventListener.add(new LeftOverTempDirPrinter());
   }
   if (firstConf['write_test_outcome_log']) {
     eventListener.add(new TestOutcomeLogWriter());
   }
   if (firstConf['copy_coredumps']) {
     eventListener.add(new UnexpectedCrashDumpArchiver());
   }
 
   eventListener.add(new ExitCodeSetter());
+  eventListener.add(new DeleteTestCaseOutput());
 
   void startProcessQueue() {
     // [firstConf] is needed here, since the ProcessQueue needs to know the
     // settings of 'noBatch' and 'local_ip'
     new ProcessQueue(firstConf,
                      maxProcesses,
                      maxBrowserProcesses,
                      startTime,
                      testSuites,
                      eventListener,
@@ skipping 33 matching lines @@
 void main(List<String> arguments) {
   deleteTemporaryDartDirectories().then((_) {
     var optionsParser = new TestOptionsParser();
     var configurations = optionsParser.parse(arguments);
     if (configurations != null && configurations.length > 0) {
       testConfigurations(configurations);
     }
   });
 }