diff --git a/tests/lib/html/fileapi_directory_reader_test.dart b/tests/lib/html/fileapi_directory_reader_test.dart
index a1b57ebf037..74687596cd9 100644
--- a/tests/lib/html/fileapi_directory_reader_test.dart
+++ b/tests/lib/html/fileapi_directory_reader_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.7
-
 library fileapi;
 
 import 'dart:async';
@@ -18,12 +16,11 @@ class FileAndDir {
   FileAndDir(this.file, this.dir);
 }
 
-FileSystem fs;
+late FileSystem fs;
 
 main() async {
   getFileSystem() async {
-    var fileSystem = await window.requestFileSystem(100);
-    fs = fileSystem;
+    fs = await window.requestFileSystem(100);
   }
 
   // Do the boilerplate to get several files and directories created to then
@@ -31,8 +28,8 @@ main() async {
   Future doDirSetup(String testName) async {
     await getFileSystem();
 
-    var file = await fs.root.createFile('file_$testName');
-    var dir = await fs.root.createDirectory('dir_$testName');
+    var file = await fs.root.createFile('file_$testName') as FileEntry;
+    var dir = await fs.root.createDirectory('dir_$testName') as DirectoryEntry;
     return new Future.value(new FileAndDir(file, dir));
   }
 
diff --git a/tests/lib/html/fileapi_directory_test.dart b/tests/lib/html/fileapi_directory_test.dart
index 679354d0d6d..b2c79451ac3 100644
--- a/tests/lib/html/fileapi_directory_test.dart
+++ b/tests/lib/html/fileapi_directory_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.7
-
 library fileapi;
 
 import 'dart:async';
@@ -18,12 +16,11 @@ class FileAndDir {
   FileAndDir(this.file, this.dir);
 }
 
-FileSystem fs;
+late FileSystem fs;
 
 main() async {
   getFileSystem() async {
-    var fileSystem = await window.requestFileSystem(100);
-    fs = fileSystem;
+    fs = await window.requestFileSystem(100);
   }
 
   if (FileSystem.supported) {
diff --git a/tests/lib/html/fileapi_entry_test.dart b/tests/lib/html/fileapi_entry_test.dart
index 41360b06757..7669fc875ee 100644
--- a/tests/lib/html/fileapi_entry_test.dart
+++ b/tests/lib/html/fileapi_entry_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.7
-
 library fileapi;
 
 import 'dart:async';
@@ -18,7 +16,7 @@ class FileAndDir {
   FileAndDir(this.file, this.dir);
 }
 
-FileSystem fs;
+late FileSystem fs;
 
 main() async {
   getFileSystem() async {
@@ -32,8 +30,8 @@ main() async {
   Future doDirSetup(String testName) async {
     await getFileSystem();
 
-    var file = await fs.root.createFile('file_$testName');
-    var dir = await fs.root.createDirectory('dir_$testName');
+    var file = await fs.root.createFile('file_$testName') as FileEntry;
+    var dir = await fs.root.createDirectory('dir_$testName') as DirectoryEntry;
     return new Future.value(new FileAndDir(file, dir));
   }
 
diff --git a/tests/lib/html/fileapi_file_entry_test.dart b/tests/lib/html/fileapi_file_entry_test.dart
index c55010980a8..1789003b50d 100644
--- a/tests/lib/html/fileapi_file_entry_test.dart
+++ b/tests/lib/html/fileapi_file_entry_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.7
-
 library fileapi;
 
 import 'dart:async';
@@ -18,12 +16,11 @@ class FileAndDir {
   FileAndDir(this.file, this.dir);
 }
 
-FileSystem fs;
+late FileSystem fs;
 
 main() async {
   getFileSystem() async {
-    var fileSystem = await window.requestFileSystem(100);
-    fs = fileSystem;
+    fs = await window.requestFileSystem(100);
   }
 
   // Do the boilerplate to get several files and directories created to then
@@ -31,8 +28,8 @@ main() async {
   Future doDirSetup(String testName) async {
     await getFileSystem();
 
-    var file = await fs.root.createFile('file_$testName');
-    var dir = await fs.root.createDirectory('dir_$testName');
+    var file = await fs.root.createFile('file_$testName') as FileEntry;
+    var dir = await fs.root.createDirectory('dir_$testName') as DirectoryEntry;
     return new Future.value(new FileAndDir(file, dir));
   }
 
diff --git a/tests/lib/html/fileapi_file_test.dart b/tests/lib/html/fileapi_file_test.dart
index 25f469f5e1c..f70bb1325e0 100644
--- a/tests/lib/html/fileapi_file_test.dart
+++ b/tests/lib/html/fileapi_file_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.7
-
 library fileapi;
 
 import 'dart:async';
@@ -18,12 +16,11 @@ class FileAndDir {
   FileAndDir(this.file, this.dir);
 }
 
-FileSystem fs;
+late FileSystem fs;
 
 main() async {
   getFileSystem() async {
-    var fileSystem = await window.requestFileSystem(100);
-    fs = fileSystem;
+    fs = await window.requestFileSystem(100);
   }
 
   if (FileSystem.supported) {
diff --git a/tests/lib/html/fileapi_supported_test.dart b/tests/lib/html/fileapi_supported_test.dart
index 36feb2f328a..75fe3b87ee4 100644
--- a/tests/lib/html/fileapi_supported_test.dart
+++ b/tests/lib/html/fileapi_supported_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.7
-
 library fileapi;
 
 import 'dart:async';
@@ -12,20 +10,18 @@ import 'dart:html';
 import 'package:async_helper/async_helper.dart';
 import 'package:async_helper/async_minitest.dart';
 
-Future<FileSystem> _fileSystem;
+Future<FileSystem>? _fileSystem;
 
 Future<FileSystem> get fileSystem async {
-  if (_fileSystem != null) return _fileSystem;
+  if (_fileSystem != null) return _fileSystem!;
 
   _fileSystem = window.requestFileSystem(100);
 
-  var fs = await _fileSystem;
-  expect(fs != null, true);
-  expect(fs.root != null, true);
+  var fs = await _fileSystem!;
   expect(fs.runtimeType, FileSystem);
   expect(fs.root.runtimeType, DirectoryEntry);
 
-  return _fileSystem;
+  return _fileSystem!;
 }
 
 main() {
@@ -37,7 +33,6 @@ main() {
     var expectation = FileSystem.supported ? returnsNormally : throws;
     expect(() async {
       var fs = await fileSystem;
-      expect(fs.root != null, true);
     }, expectation);
   });
 }