Revert "Remove "unnecessary" imports. (#79610)" (#80070)

This reverts commit 98a96189.

dev/tools/test/common.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:dev_tools/stdio.dart';

dev/tracing_tests/test/image_painting_event_test.dart

@@ -7,6 +7,7 @@ import 'dart:convert' show jsonEncode;
 import 'dart:developer' as developer;
 import 'dart:ui' as ui;
 
+import 'package:flutter/painting.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:vm_service/vm_service.dart';

packages/flutter/lib/src/widgets/text_editing_action.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart' show RenderEditable;
 
 import 'actions.dart';

packages/flutter/test/material/elevated_button_theme_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {

packages/flutter/test/material/outlined_button_theme_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {

packages/flutter/test/material/text_button_theme_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {