some whitespace cleanup (#14443)

diff --git a/packages/flutter_tools/test/cache_test.dart b/packages/flutter_tools/test/cache_test.dart
index b8fe08a..fb8fd5c 100644
--- a/packages/flutter_tools/test/cache_test.dart
+++ b/packages/flutter_tools/test/cache_test.dart
@@ -82,7 +82,7 @@
     expect(flattenNameSubdirs(Uri.parse('http://flutter.io/foo/bar')), 'flutter.io/foo/bar');
     expect(flattenNameSubdirs(Uri.parse('http://docs.flutter.io/foo/bar')), 'docs.flutter.io/foo/bar');
     expect(flattenNameSubdirs(Uri.parse('https://www.flutter.io')), 'www.flutter.io');
-  },  overrides: <Type, Generator>{
+  }, overrides: <Type, Generator>{
     FileSystem: () => new MockFileSystem(),
   });
 }