some whitespace cleanup (#14443)

diff --git a/examples/flutter_gallery/lib/demo/material/drawer_demo.dart b/examples/flutter_gallery/lib/demo/material/drawer_demo.dart
index 8d96bd5..54f6f35 100644
--- a/examples/flutter_gallery/lib/demo/material/drawer_demo.dart
+++ b/examples/flutter_gallery/lib/demo/material/drawer_demo.dart
@@ -100,7 +100,7 @@
                   package: _kGalleryAssetsPackage,
                 ),
               ),
-              otherAccountsPictures:  <Widget>[
+              otherAccountsPictures: <Widget>[
                 new GestureDetector(
                   onTap: () {
                     _onOtherAccountsTap(context);