Remove "unnecessary" imports in tests (#75705)

packages/flutter/test/rendering/reattach_test.dart

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

packages/flutter/test/rendering/recording_canvas.dart

@@ -2,9 +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';
-import 'package:flutter/src/rendering/layer.dart';
 
 /// An [Invocation] and the [stack] trace that led to it.
 ///

packages/flutter/test/rendering/repaint_boundary_test.dart

@@ -2,7 +2,6 @@
 // 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';
 import '../flutter_test_alternative.dart';
 

packages/flutter/test/rendering/simple_semantics_test.dart

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

packages/flutter/test/rendering/slivers_test.dart

@@ -2,10 +2,8 @@
 // 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/gestures.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:vector_math/vector_math_64.dart';
 

packages/flutter/test/rendering/view_chrome_style_test.dart

@@ -4,9 +4,7 @@
 
 import 'dart:ui';
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter/test/rendering/viewport_test.dart

@@ -7,8 +7,6 @@
 // initialize a binding, which rendering_tester will attempt to re-initialize
 // (or vice versa).
 
-import 'dart:ui';
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';

packages/flutter/test/scheduler/benchmarks_test.dart

@@ -2,7 +2,6 @@
 // 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/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter/test/semantics/semantics_elevation_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 import '../widgets/semantics_tester.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:vector_math/vector_math_64.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter/test/semantics/traversal_order_test.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 import '../widgets/semantics_tester.dart';