Fix recursive directory-deletion of top-level files/links.

tests/standalone/io/directory_error_test.dart

Index: tests/standalone/io/directory_error_test.dart
diff --git a/tests/standalone/io/directory_error_test.dart b/tests/standalone/io/directory_error_test.dart
index 2d1c0b7ea429ca9fd8dc9d7012ed0f7a14c7ef0f..33418ef175499c719f9689fc2ce07b348256a81a 100644
--- a/tests/standalone/io/directory_error_test.dart
+++ b/tests/standalone/io/directory_error_test.dart
@@ -95,13 +95,8 @@ bool checkDeleteRecursivelyNonExistentFileException(e) {
   Expect.isTrue(e is DirectoryIOException);
   Expect.isTrue(e.osError != null);
   Expect.isTrue(e.toString().indexOf("Deletion failed") != -1);
-  if (Platform.operatingSystem == "linux") {
-    Expect.equals(2, e.osError.errorCode);
-  } else if (Platform.operatingSystem == "macos") {
-    Expect.equals(2, e.osError.errorCode);
-  } else if (Platform.operatingSystem == "windows") {
-    Expect.equals(3, e.osError.errorCode);
-  }
+  // File not not found has error code 2 on all supported platforms.
+  Expect.equals(2, e.osError.errorCode);
 
   return true;
 }