apply the upcoming rule : directives_ordering (#8582)

examples/flutter_gallery/lib/demo/all.dart

@@ -6,8 +6,8 @@ export 'animation_demo.dart';
 export 'calculator_demo.dart';
 export 'colors_demo.dart';
 export 'contacts_demo.dart';
+export 'cupertino/cupertino.dart';
+export 'material/material.dart';
 export 'pesto_demo.dart';
 export 'shrine_demo.dart';
 export 'typography_demo.dart';
-export 'cupertino/cupertino.dart';
-export 'material/material.dart';

packages/flutter/lib/src/material/back_button.dart

@@ -4,10 +4,10 @@
 
 import 'package:flutter/widgets.dart';
 
-import 'theme.dart';
-import 'icon_button.dart';
 import 'icon.dart';
+import 'icon_button.dart';
 import 'icons.dart';
+import 'theme.dart';
 
 /// A material design back button.
 ///

packages/flutter_tools/test/all.dart

@@ -42,12 +42,12 @@ import 'os_utils_test.dart' as os_utils_test;
 import 'packages_test.dart' as packages_test;
 import 'protocol_discovery_test.dart' as protocol_discovery_test;
 import 'run_test.dart' as run_test;
+import 'src/base/process_test.dart' as process_test;
 import 'stop_test.dart' as stop_test;
 import 'test_test.dart' as test_test;
 import 'trace_test.dart' as trace_test;
 import 'upgrade_test.dart' as upgrade_test;
 import 'utils_test.dart' as utils_test;
-import 'src/base/process_test.dart' as process_test;
 
 void main() {
   Cache.disableLocking();