diff --git a/dev/devicelab/bin/tasks/analyzer_benchmark.dart b/dev/devicelab/bin/tasks/analyzer_benchmark.dart
index 3ded9ba7fc..c8d092a049 100644
--- a/dev/devicelab/bin/tasks/analyzer_benchmark.dart
+++ b/dev/devicelab/bin/tasks/analyzer_benchmark.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/analysis.dart';
 
diff --git a/dev/devicelab/bin/tasks/android_defines_test.dart b/dev/devicelab/bin/tasks/android_defines_test.dart
index 9774212a1d..2f31c1133f 100644
--- a/dev/devicelab/bin/tasks/android_defines_test.dart
+++ b/dev/devicelab/bin/tasks/android_defines_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/android_engine_dependency_proxy_test.dart b/dev/devicelab/bin/tasks/android_engine_dependency_proxy_test.dart
index 69a663f390..314854d0d0 100644
--- a/dev/devicelab/bin/tasks/android_engine_dependency_proxy_test.dart
+++ b/dev/devicelab/bin/tasks/android_engine_dependency_proxy_test.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
@@ -20,7 +18,7 @@ Future<void> main() async {
   await task(() async {
     section('Find Java');
 
-    final String javaHome = await findJavaHome();
+    final String? javaHome = await findJavaHome();
     if (javaHome == null)
       return TaskResult.failure('Could not find Java');
     print('\nUsing JAVA_HOME=$javaHome');
diff --git a/dev/devicelab/bin/tasks/android_obfuscate_test.dart b/dev/devicelab/bin/tasks/android_obfuscate_test.dart
index 7e4429e413..6676a0d61f 100644
--- a/dev/devicelab/bin/tasks/android_obfuscate_test.dart
+++ b/dev/devicelab/bin/tasks/android_obfuscate_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/task_result.dart';
diff --git a/dev/devicelab/bin/tasks/android_semantics_integration_test.dart b/dev/devicelab/bin/tasks/android_semantics_integration_test.dart
index d2ce3e47f7..415fad2eca 100644
--- a/dev/devicelab/bin/tasks/android_semantics_integration_test.dart
+++ b/dev/devicelab/bin/tasks/android_semantics_integration_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/android_stack_size_test.dart b/dev/devicelab/bin/tasks/android_stack_size_test.dart
index 546aef2d79..80341ffa24 100644
--- a/dev/devicelab/bin/tasks/android_stack_size_test.dart
+++ b/dev/devicelab/bin/tasks/android_stack_size_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/android_view_scroll_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/android_view_scroll_perf__timeline_summary.dart
index 22e2df478f..1112ba20e8 100644
--- a/dev/devicelab/bin/tasks/android_view_scroll_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/android_view_scroll_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/animated_image_gc_perf.dart b/dev/devicelab/bin/tasks/animated_image_gc_perf.dart
index 65f456ee30..b5fe9f8e0c 100644
--- a/dev/devicelab/bin/tasks/animated_image_gc_perf.dart
+++ b/dev/devicelab/bin/tasks/animated_image_gc_perf.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
diff --git a/dev/devicelab/bin/tasks/animated_placeholder_perf__e2e_summary.dart b/dev/devicelab/bin/tasks/animated_placeholder_perf__e2e_summary.dart
index ec033b3bff..e8986d8930 100644
--- a/dev/devicelab/bin/tasks/animated_placeholder_perf__e2e_summary.dart
+++ b/dev/devicelab/bin/tasks/animated_placeholder_perf__e2e_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/animation_with_microtasks_perf_ios__timeline_summary.dart b/dev/devicelab/bin/tasks/animation_with_microtasks_perf_ios__timeline_summary.dart
index c84450eda7..8ecc0bacff 100644
--- a/dev/devicelab/bin/tasks/animation_with_microtasks_perf_ios__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/animation_with_microtasks_perf_ios__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/backdrop_filter_perf__e2e_summary.dart b/dev/devicelab/bin/tasks/backdrop_filter_perf__e2e_summary.dart
index 49b216f515..141e2c23b6 100644
--- a/dev/devicelab/bin/tasks/backdrop_filter_perf__e2e_summary.dart
+++ b/dev/devicelab/bin/tasks/backdrop_filter_perf__e2e_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart
index db1ec8f7b9..1b59f9da0e 100644
--- a/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/backdrop_filter_perf_ios__timeline_summary.dart b/dev/devicelab/bin/tasks/backdrop_filter_perf_ios__timeline_summary.dart
index 354d3694ea..6a63a8b916 100644
--- a/dev/devicelab/bin/tasks/backdrop_filter_perf_ios__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/backdrop_filter_perf_ios__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/basic_material_app_android__compile.dart b/dev/devicelab/bin/tasks/basic_material_app_android__compile.dart
index 6b93fad7d7..cf903c03f9 100644
--- a/dev/devicelab/bin/tasks/basic_material_app_android__compile.dart
+++ b/dev/devicelab/bin/tasks/basic_material_app_android__compile.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/basic_material_app_ios__compile.dart b/dev/devicelab/bin/tasks/basic_material_app_ios__compile.dart
index e503d0a5ed..cc6f0f7c2c 100644
--- a/dev/devicelab/bin/tasks/basic_material_app_ios__compile.dart
+++ b/dev/devicelab/bin/tasks/basic_material_app_ios__compile.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/basic_material_app_win__compile.dart b/dev/devicelab/bin/tasks/basic_material_app_win__compile.dart
index 6b93fad7d7..cf903c03f9 100644
--- a/dev/devicelab/bin/tasks/basic_material_app_win__compile.dart
+++ b/dev/devicelab/bin/tasks/basic_material_app_win__compile.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/build_aar_module_test.dart b/dev/devicelab/bin/tasks/build_aar_module_test.dart
index 5c03498aff..3a78801ad6 100644
--- a/dev/devicelab/bin/tasks/build_aar_module_test.dart
+++ b/dev/devicelab/bin/tasks/build_aar_module_test.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
@@ -24,7 +22,7 @@ Future<void> main() async {
 
     section('Find Java');
 
-    final String javaHome = await findJavaHome();
+    final String? javaHome = await findJavaHome();
     if (javaHome == null)
       return TaskResult.failure('Could not find Java');
     print('\nUsing JAVA_HOME=$javaHome');
diff --git a/dev/devicelab/bin/tasks/build_aar_plugin_test.dart b/dev/devicelab/bin/tasks/build_aar_plugin_test.dart
index 6f666d2660..e0df9586d1 100644
--- a/dev/devicelab/bin/tasks/build_aar_plugin_test.dart
+++ b/dev/devicelab/bin/tasks/build_aar_plugin_test.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
@@ -20,7 +18,7 @@ Future<void> main() async {
 
     section('Find Java');
 
-    final String javaHome = await findJavaHome();
+    final String? javaHome = await findJavaHome();
     if (javaHome == null)
       return TaskResult.failure('Could not find Java');
     print('\nUsing JAVA_HOME=$javaHome');
diff --git a/dev/devicelab/bin/tasks/build_ios_framework_module_test.dart b/dev/devicelab/bin/tasks/build_ios_framework_module_test.dart
index 05fd14d5c0..63b59ab28c 100644
--- a/dev/devicelab/bin/tasks/build_ios_framework_module_test.dart
+++ b/dev/devicelab/bin/tasks/build_ios_framework_module_test.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
diff --git a/dev/devicelab/bin/tasks/build_mode_test.dart b/dev/devicelab/bin/tasks/build_mode_test.dart
index 23f739bab5..e73625a9a9 100644
--- a/dev/devicelab/bin/tasks/build_mode_test.dart
+++ b/dev/devicelab/bin/tasks/build_mode_test.dart
@@ -2,8 +2,6 @@
 // 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:convert';
 import 'dart:io';
@@ -25,7 +23,7 @@ Future<String> runFlutterAndQuit(List<String> args, Device device) async {
   );
   final List<String> stdout = <String>[];
   final List<String> stderr = <String>[];
-  int runExitCode;
+  int? runExitCode;
   run.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(
     (String line) {
       print('run:stdout: $line');
diff --git a/dev/devicelab/bin/tasks/channels_integration_test.dart b/dev/devicelab/bin/tasks/channels_integration_test.dart
index e842be1b6c..c1cb7b8e8b 100644
--- a/dev/devicelab/bin/tasks/channels_integration_test.dart
+++ b/dev/devicelab/bin/tasks/channels_integration_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/channels_integration_test_ios.dart b/dev/devicelab/bin/tasks/channels_integration_test_ios.dart
index 9445f9b1bb..41f042291c 100644
--- a/dev/devicelab/bin/tasks/channels_integration_test_ios.dart
+++ b/dev/devicelab/bin/tasks/channels_integration_test_ios.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/channels_integration_test_win.dart b/dev/devicelab/bin/tasks/channels_integration_test_win.dart
index e842be1b6c..c1cb7b8e8b 100644
--- a/dev/devicelab/bin/tasks/channels_integration_test_win.dart
+++ b/dev/devicelab/bin/tasks/channels_integration_test_win.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/codegen_integration_linux.dart b/dev/devicelab/bin/tasks/codegen_integration_linux.dart
index f7dae49a44..57eab92aeb 100644
--- a/dev/devicelab/bin/tasks/codegen_integration_linux.dart
+++ b/dev/devicelab/bin/tasks/codegen_integration_linux.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/codegen_integration_mac.dart b/dev/devicelab/bin/tasks/codegen_integration_mac.dart
index 2501d7b7b7..a1d76af3e3 100644
--- a/dev/devicelab/bin/tasks/codegen_integration_mac.dart
+++ b/dev/devicelab/bin/tasks/codegen_integration_mac.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/codegen_integration_win.dart b/dev/devicelab/bin/tasks/codegen_integration_win.dart
index f7dae49a44..57eab92aeb 100644
--- a/dev/devicelab/bin/tasks/codegen_integration_win.dart
+++ b/dev/devicelab/bin/tasks/codegen_integration_win.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/color_filter_and_fade_perf__e2e_summary.dart b/dev/devicelab/bin/tasks/color_filter_and_fade_perf__e2e_summary.dart
index e63db6ecfe..5ec07b7c7f 100644
--- a/dev/devicelab/bin/tasks/color_filter_and_fade_perf__e2e_summary.dart
+++ b/dev/devicelab/bin/tasks/color_filter_and_fade_perf__e2e_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/color_filter_and_fade_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/color_filter_and_fade_perf__timeline_summary.dart
index 62439a7eb4..234b43b456 100644
--- a/dev/devicelab/bin/tasks/color_filter_and_fade_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/color_filter_and_fade_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout__start_up.dart b/dev/devicelab/bin/tasks/complex_layout__start_up.dart
index c05c700cb2..12c6d9a862 100644
--- a/dev/devicelab/bin/tasks/complex_layout__start_up.dart
+++ b/dev/devicelab/bin/tasks/complex_layout__start_up.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_android__compile.dart b/dev/devicelab/bin/tasks/complex_layout_android__compile.dart
index 41ad9847cc..4bc85ca1c2 100644
--- a/dev/devicelab/bin/tasks/complex_layout_android__compile.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_android__compile.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_android__scroll_smoothness.dart b/dev/devicelab/bin/tasks/complex_layout_android__scroll_smoothness.dart
index 0503f77648..7fe5461cc4 100644
--- a/dev/devicelab/bin/tasks/complex_layout_android__scroll_smoothness.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_android__scroll_smoothness.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_ios__compile.dart b/dev/devicelab/bin/tasks/complex_layout_ios__compile.dart
index 36fd39a284..d8600c22cb 100644
--- a/dev/devicelab/bin/tasks/complex_layout_ios__compile.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_ios__compile.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_ios__start_up.dart b/dev/devicelab/bin/tasks/complex_layout_ios__start_up.dart
index 4548bffb38..2bb3a26924 100644
--- a/dev/devicelab/bin/tasks/complex_layout_ios__start_up.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_ios__start_up.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_scroll_perf__devtools_memory.dart b/dev/devicelab/bin/tasks/complex_layout_scroll_perf__devtools_memory.dart
index 94f0614f99..de449f3b59 100644
--- a/dev/devicelab/bin/tasks/complex_layout_scroll_perf__devtools_memory.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_scroll_perf__devtools_memory.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_scroll_perf__memory.dart b/dev/devicelab/bin/tasks/complex_layout_scroll_perf__memory.dart
index 8b0146fb7b..f3784a3b30 100644
--- a/dev/devicelab/bin/tasks/complex_layout_scroll_perf__memory.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_scroll_perf__memory.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_scroll_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/complex_layout_scroll_perf__timeline_summary.dart
index 95cb14fce0..d4f1878846 100644
--- a/dev/devicelab/bin/tasks/complex_layout_scroll_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_scroll_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_scroll_perf_ios__timeline_summary.dart b/dev/devicelab/bin/tasks/complex_layout_scroll_perf_ios__timeline_summary.dart
index b9a3cd7dd8..b514d35741 100644
--- a/dev/devicelab/bin/tasks/complex_layout_scroll_perf_ios__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_scroll_perf_ios__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_semantics_perf.dart b/dev/devicelab/bin/tasks/complex_layout_semantics_perf.dart
index 0a40d263f9..ab1d4b7c12 100644
--- a/dev/devicelab/bin/tasks/complex_layout_semantics_perf.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_semantics_perf.dart
@@ -2,8 +2,6 @@
 // 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:io';
 
 import 'package:flutter_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/complex_layout_win__compile.dart b/dev/devicelab/bin/tasks/complex_layout_win__compile.dart
index 41ad9847cc..4bc85ca1c2 100644
--- a/dev/devicelab/bin/tasks/complex_layout_win__compile.dart
+++ b/dev/devicelab/bin/tasks/complex_layout_win__compile.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/cubic_bezier_perf__e2e_summary.dart b/dev/devicelab/bin/tasks/cubic_bezier_perf__e2e_summary.dart
index 4dfb8c5237..437982f508 100644
--- a/dev/devicelab/bin/tasks/cubic_bezier_perf__e2e_summary.dart
+++ b/dev/devicelab/bin/tasks/cubic_bezier_perf__e2e_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/cubic_bezier_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/cubic_bezier_perf__timeline_summary.dart
index 352f559110..2a1ad712d5 100644
--- a/dev/devicelab/bin/tasks/cubic_bezier_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/cubic_bezier_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__e2e_summary.dart b/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__e2e_summary.dart
index 0bad40559a..38d83b1e21 100644
--- a/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__e2e_summary.dart
+++ b/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__e2e_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
diff --git a/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__timeline_summary.dart b/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__timeline_summary.dart
index ae086b4928..83eb00361c 100644
--- a/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/cubic_bezier_perf_sksl_warmup__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/cull_opacity_perf__e2e_summary.dart b/dev/devicelab/bin/tasks/cull_opacity_perf__e2e_summary.dart
index 2e6adeca8b..593641abac 100644
--- a/dev/devicelab/bin/tasks/cull_opacity_perf__e2e_summary.dart
+++ b/dev/devicelab/bin/tasks/cull_opacity_perf__e2e_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/cull_opacity_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/cull_opacity_perf__timeline_summary.dart
index b51ded429c..9840170a09 100644
--- a/dev/devicelab/bin/tasks/cull_opacity_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/cull_opacity_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/dart_plugin_registry_test.dart b/dev/devicelab/bin/tasks/dart_plugin_registry_test.dart
index 1ddd1213c4..1688aadf79 100644
--- a/dev/devicelab/bin/tasks/dart_plugin_registry_test.dart
+++ b/dev/devicelab/bin/tasks/dart_plugin_registry_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/dart_plugin_registry_tests.dart';
 
diff --git a/dev/devicelab/bin/tasks/dartdocs.dart b/dev/devicelab/bin/tasks/dartdocs.dart
index 0a11a2e37b..0bb2d2093c 100644
--- a/dev/devicelab/bin/tasks/dartdocs.dart
+++ b/dev/devicelab/bin/tasks/dartdocs.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/task_result.dart';
 
diff --git a/dev/devicelab/bin/tasks/devtools_profile_start_test.dart b/dev/devicelab/bin/tasks/devtools_profile_start_test.dart
index 5d1f8afe4f..11959b5bc4 100644
--- a/dev/devicelab/bin/tasks/devtools_profile_start_test.dart
+++ b/dev/devicelab/bin/tasks/devtools_profile_start_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
diff --git a/dev/devicelab/bin/tasks/drive_perf_debug_warning.dart b/dev/devicelab/bin/tasks/drive_perf_debug_warning.dart
index 08be167624..0390ad891e 100644
--- a/dev/devicelab/bin/tasks/drive_perf_debug_warning.dart
+++ b/dev/devicelab/bin/tasks/drive_perf_debug_warning.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/task_result.dart';
diff --git a/dev/devicelab/bin/tasks/embedded_android_views_integration_test.dart b/dev/devicelab/bin/tasks/embedded_android_views_integration_test.dart
index 8bf3425e8c..c13bc789f0 100644
--- a/dev/devicelab/bin/tasks/embedded_android_views_integration_test.dart
+++ b/dev/devicelab/bin/tasks/embedded_android_views_integration_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/external_ui_integration_test.dart b/dev/devicelab/bin/tasks/external_ui_integration_test.dart
index 793bd5c719..cc0930ea73 100644
--- a/dev/devicelab/bin/tasks/external_ui_integration_test.dart
+++ b/dev/devicelab/bin/tasks/external_ui_integration_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/external_ui_integration_test_ios.dart b/dev/devicelab/bin/tasks/external_ui_integration_test_ios.dart
index 3174d152a6..a573cc1b61 100644
--- a/dev/devicelab/bin/tasks/external_ui_integration_test_ios.dart
+++ b/dev/devicelab/bin/tasks/external_ui_integration_test_ios.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/fading_child_animation_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/fading_child_animation_perf__timeline_summary.dart
index 14ea384c1d..dbed0b3c4d 100644
--- a/dev/devicelab/bin/tasks/fading_child_animation_perf__timeline_summary.dart
+++ b/dev/devicelab/bin/tasks/fading_child_animation_perf__timeline_summary.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
diff --git a/dev/devicelab/bin/tasks/fast_scroll_heavy_gridview__memory.dart b/dev/devicelab/bin/tasks/fast_scroll_heavy_gridview__memory.dart
index 3d7d393339..9c8c38bada 100644
--- a/dev/devicelab/bin/tasks/fast_scroll_heavy_gridview__memory.dart
+++ b/dev/devicelab/bin/tasks/fast_scroll_heavy_gridview__memory.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
@@ -20,7 +18,7 @@ class FastScrollHeavyGridViewMemoryTest extends MemoryTest {
         );
 
   @override
-  AndroidDevice get device => super.device as AndroidDevice;
+  AndroidDevice? get device => super.device as AndroidDevice?;
 
   @override
   int get iterationCount => 5;
@@ -29,11 +27,11 @@ class FastScrollHeavyGridViewMemoryTest extends MemoryTest {
   Future<void> useMemory() async {
     await launchApp();
     await recordStart();
-    await device.shellExec('input', <String>['swipe', '50 1500 50 50 50']);
+    await device!.shellExec('input', <String>['swipe', '50 1500 50 50 50']);
     await Future<void>.delayed(const Duration(milliseconds: 1500));
-    await device.shellExec('input', <String>['swipe', '50 1500 50 50 50']);
+    await device!.shellExec('input', <String>['swipe', '50 1500 50 50 50']);
     await Future<void>.delayed(const Duration(milliseconds: 1500));
-    await device.shellExec('input', <String>['swipe', '50 1500 50 50 50']);
+    await device!.shellExec('input', <String>['swipe', '50 1500 50 50 50']);
     await Future<void>.delayed(const Duration(milliseconds: 1500));
     await recordEnd();
   }
diff --git a/dev/devicelab/bin/tasks/fast_scroll_large_images__memory.dart b/dev/devicelab/bin/tasks/fast_scroll_large_images__memory.dart
index e61adf6c7e..26b76c2a41 100644
--- a/dev/devicelab/bin/tasks/fast_scroll_large_images__memory.dart
+++ b/dev/devicelab/bin/tasks/fast_scroll_large_images__memory.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
@@ -20,7 +18,7 @@ class FastScrollLargeImagesMemoryTest extends MemoryTest {
         );
 
   @override
-  AndroidDevice get device => super.device as AndroidDevice;
+  AndroidDevice? get device => super.device as AndroidDevice?;
 
   @override
   int get iterationCount => 5;
@@ -29,7 +27,7 @@ class FastScrollLargeImagesMemoryTest extends MemoryTest {
   Future<void> useMemory() async {
     await launchApp();
     await recordStart();
-    await device.shellExec('input', <String>['swipe', '0 1500 0 0 50']);
+    await device!.shellExec('input', <String>['swipe', '0 1500 0 0 50']);
     await Future<void>.delayed(const Duration(milliseconds: 15000));
     await recordEnd();
   }
diff --git a/dev/devicelab/bin/tasks/flavors_test.dart b/dev/devicelab/bin/tasks/flavors_test.dart
index 92e1522b6e..b8fbade661 100644
--- a/dev/devicelab/bin/tasks/flavors_test.dart
+++ b/dev/devicelab/bin/tasks/flavors_test.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/flavors_test_ios.dart b/dev/devicelab/bin/tasks/flavors_test_ios.dart
index c20de247a2..3fa97b2cf7 100644
--- a/dev/devicelab/bin/tasks/flavors_test_ios.dart
+++ b/dev/devicelab/bin/tasks/flavors_test_ios.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';
diff --git a/dev/devicelab/bin/tasks/flavors_test_win.dart b/dev/devicelab/bin/tasks/flavors_test_win.dart
index 92e1522b6e..b8fbade661 100644
--- a/dev/devicelab/bin/tasks/flavors_test_win.dart
+++ b/dev/devicelab/bin/tasks/flavors_test_win.dart
@@ -2,8 +2,6 @@
 // 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_devicelab/framework/devices.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/integration_tests.dart';