Migrate layout/ to null safety

lib/codeviewer/code_displayer.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 typedef CodeDisplayer = TextSpan Function(BuildContext context);

lib/codeviewer/code_style.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 class CodeStyle extends InheritedWidget {

lib/constants.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 // Only put constants shared between files here.
 
 // height of the 'Gallery' header

lib/data/demos.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'dart:collection';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';

lib/data/gallery_options.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'dart:async';
 
 import 'package:flutter/material.dart';

lib/data/icons.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 class GalleryIcons {

lib/deferred_widget.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'dart:async';
 import 'package:flutter/material.dart';
 

lib/demos/cupertino/cupertino_activity_indicator_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/cupertino/cupertino_alert_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_button_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_context_menu_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_demos.dart

@@ -1,3 +1,5 @@
+// @dart=2.9
+
 export 'package:gallery/demos/cupertino/cupertino_activity_indicator_demo.dart';
 export 'package:gallery/demos/cupertino/cupertino_alert_demo.dart';
 export 'package:gallery/demos/cupertino/cupertino_button_demo.dart';

lib/demos/cupertino/cupertino_navigation_bar_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_picker_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:intl/intl.dart';

lib/demos/cupertino/cupertino_refresh_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'dart:math' show Random;
 
 import 'package:flutter/cupertino.dart';

lib/demos/cupertino/cupertino_segmented_control_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_slider_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_switch_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_tab_bar_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/cupertino/cupertino_text_field_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/cupertino/demo_types.dart

@@ -1,3 +1,5 @@
+// @dart=2.9
+
 enum AlertDemoType {
   alert,
   alertTitle,

lib/demos/material/app_bar_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/banner_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/bottom_app_bar_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/bottom_navigation_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:animations/animations.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/bottom_sheet_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/button_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/cards_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/chip_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/demos/material/material_demo_types.dart';

lib/demos/material/data_table_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/data/gallery_options.dart';

lib/demos/material/dialog_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/divider_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/demos/material/material_demo_types.dart';

lib/demos/material/grid_list_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/demos/material/material_demo_types.dart';

lib/demos/material/list_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/material_demo_types.dart

@@ -1,3 +1,5 @@
+// @dart=2.9
+
 enum BottomNavigationDemoType {
   withLabels,
   withoutLabels,

lib/demos/material/material_demos.dart

@@ -1,3 +1,5 @@
+// @dart=2.9
+
 export 'package:gallery/demos/material/app_bar_demo.dart';
 export 'package:gallery/demos/material/banner_demo.dart';
 export 'package:gallery/demos/material/bottom_app_bar_demo.dart';

lib/demos/material/menu_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/navigation_drawer.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/navigation_rail_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/picker_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/demos/material/material_demo_types.dart';

lib/demos/material/progress_indicator_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/demos/material/material_demo_types.dart';

lib/demos/material/selection_controls_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';

lib/demos/material/sliders_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'dart:math' as math;
 
 import 'package:flutter/material.dart';

lib/demos/material/snackbar_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 

lib/demos/material/tabs_demo.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 import 'package:gallery/demos/material/material_demo_types.dart';