[multiple] Opt-out tests of null-safety (flutter#3113)

Author: ditman

packages/connectivity/connectivity/test/connectivity_test.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 = 2.8
+
 import 'package:connectivity/connectivity.dart';
 import 'package:connectivity_platform_interface/connectivity_platform_interface.dart';
 import 'package:flutter_test/flutter_test.dart';

packages/google_sign_in/google_sign_in/test/google_sign_in_test.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 = 2.8
+
 import 'dart:async';
 
 import 'package:flutter/services.dart';

packages/shared_preferences/shared_preferences/test/shared_preferences_test.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 = 2.8
+
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:shared_preferences/shared_preferences.dart';

packages/url_launcher/url_launcher/test/url_launcher_test.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 = 2.8
+
 import 'dart:async';
 import 'dart:ui';
 import 'package:flutter_test/flutter_test.dart';

packages/video_player/video_player/test/video_player_initialization_test.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 = 2.8
+
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:video_player/video_player.dart';

packages/video_player/video_player/test/video_player_test.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 = 2.8
+
 import 'dart:async';
 import 'dart:io';