Provisionally stop working around issues 9252 and 9253.

pkg/scheduled_test/test/scheduled_process_test.dart

Index: pkg/scheduled_test/test/scheduled_process_test.dart
diff --git a/pkg/scheduled_test/test/scheduled_process_test.dart b/pkg/scheduled_test/test/scheduled_process_test.dart
index aee756fe5e0a40ab7fc900ec3b8b3f7131f739b9..66b288f6ce63859e3ff01b83d85630bcd1ba27dd 100644
--- a/pkg/scheduled_test/test/scheduled_process_test.dart
+++ b/pkg/scheduled_test/test/scheduled_process_test.dart
@@ -383,7 +383,7 @@ ScheduledProcess startDartProcess(String script) {
   currentSchedule.onComplete.schedule(() {
     return tempDir.catchError((_) => null).then((dir) {
       if (dir == null) return;
-      return deleteDir(dir);
+      return new Directory(dir).delete(recursive: true);
     });
   }, 'clean up temp dir');