Remove "unnecessary" imports. (#85736)

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

@@ -9,7 +9,6 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/semantics.dart';
 import 'package:flutter/services.dart';
 
 import 'actions.dart';

packages/flutter/test/material/material_state_mixin_test.dart

@@ -4,7 +4,6 @@
 
 import 'dart:async';
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter/test/semantics/semantics_test.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:flutter/rendering.dart';
-import 'package:flutter/semantics.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:vector_math/vector_math_64.dart';
 

packages/flutter_tools/test/general.shard/preview_device_test.dart

@@ -24,7 +24,6 @@ import 'package:test/fake.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
-import '../src/fake_process_manager.dart';
 
 void main() {
   testWithoutContext('PreviewDevice defaults', () async {