Missing trailing commas (#41473)

* add missing trailing commas

* add more missing trailing commas

* add more and more missing trailing commas

packages/flutter_tools/test/general.shard/devfs_test.dart

diff --git a/packages/flutter_tools/test/general.shard/devfs_test.dart b/packages/flutter_tools/test/general.shard/devfs_test.dart
index 351d6c8..a892efa 100644
--- a/packages/flutter_tools/test/general.shard/devfs_test.dart
+++ b/packages/flutter_tools/test/general.shard/devfs_test.dart
@@ -415,4 +415,4 @@
 class MockOddlyFailingHttpClient extends Mock implements HttpClient {}
 class MockHttpClientRequest extends Mock implements HttpClientRequest {}
 class MockHttpHeaders extends Mock implements HttpHeaders {}
-class MockHttpClientResponse extends Mock implements HttpClientResponse {}
\ No newline at end of file
+class MockHttpClientResponse extends Mock implements HttpClientResponse {}