fix some formatting issues (#25474)

diff --git a/packages/flutter_driver/test/common.dart b/packages/flutter_driver/test/common.dart
index b10f9b3..2f89c7c 100644
--- a/packages/flutter_driver/test/common.dart
+++ b/packages/flutter_driver/test/common.dart
@@ -24,4 +24,4 @@
   } on FileSystemException catch (error) {
     print('Failed to delete ${directory.path}: $error');
   }
-}
\ No newline at end of file
+}