Use dart:io directory deletion instead of starting a process.

tools/testing/dart/test_runner.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 891 matching lines @@
       if (_tests.isEmpty() && _numProcesses == 0) {
         _terminateBatchRunners();
         if (_keepGeneratedTests || _temporaryDirectory == null) {
           _cleanupAndMarkDone();
         } else if (!_temporaryDirectory.startsWith('/tmp/') ||
                    _temporaryDirectory.contains('/../')) {
           // Let's be extra careful, since rm -rf is so dangerous.
           print('Temporary directory $_temporaryDirectory unsafe to delete!');
           _cleanupAndMarkDone();
         } else {
-          // TODO(dart:1211): Use delete(recursive=true) in Dart when it is
-          // implemented, and add Windows support.
-          var deletion =
-              new Process.start('/bin/rm', ['-rf', _temporaryDirectory]);
-          deletion.onExit = (int exitCode) {
-            if (exitCode == 0) {
-              if (!_listTests) {  // Output of --list option is used by scripts.
-                print('\nTemporary directory $_temporaryDirectory deleted.');
-              }
-            } else {
-              print('\nDeletion of temp dir $_temporaryDirectory failed.');
-            }
+          Directory dir = new Directory(_temporaryDirectory);
+          dir.deleteRecursively(() {
             _cleanupAndMarkDone();
+          });
+          dir.onError = (err) {
+            print('\nDeletion of temp dir $_temporaryDirectory failed: $err');
           };
         }
       }
     }
   }
 
   /**
    * True if we are using a browser + platform combination that needs the
    * Selenium server jar.
    */
@@ skipping 176 matching lines @@
         // the developer doesn't waste his or her time trying to fix a bunch of
         // tests that appear to be broken but were actually just flakes that
         // didn't get retried because there had already been one failure.
         bool allowRetry = _MAX_FAILED_NO_RETRY > _progress.numFailedTests;
         new RunningProcess(test, allowRetry, this).start();
       }
       _numProcesses++;
     }
   }
 }