Revert "fix paint order of ink feature (#59108)" (#60530)

This reverts commit 1e843bb6.

packages/flutter/lib/src/material/app_bar.dart

@@ -684,12 +684,7 @@ class _AppBarState extends State<AppBar> {
         fit: StackFit.passthrough,
         children: <Widget>[
           widget.flexibleSpace,
-          // Creates a material widget to prevent the flexibleSpace from swallow
-          // the ink splash effect.
-          Material(
-            type: MaterialType.transparency,
-            child: appBar,
-          ),
+          appBar,
         ],
       );
     }

packages/flutter/test/material/app_bar_test.dart

@@ -10,7 +10,6 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-import '../rendering/mock_canvas.dart';
 import '../widgets/semantics_tester.dart';
 
 Widget buildSliverAppBarApp({
@@ -1104,48 +1103,6 @@ void main() {
     expect(find.byIcon(Icons.menu), findsNothing);
   });
 
-  testWidgets('AppBar ink splash draw on the correct canvas', (WidgetTester tester) async {
-    // This is a regression test for https://github.com/flutter/flutter/issues/58665
-    final Key key = UniqueKey();
-    await tester.pumpWidget(
-      MaterialApp(
-        home: Center(
-          child: AppBar(
-            title: const Text('Abc'),
-            actions: <Widget>[
-              IconButton(
-                key: key,
-                icon: const Icon(Icons.add_circle),
-                tooltip: 'First button',
-                onPressed: () {},
-              ),
-            ],
-            flexibleSpace: DecoratedBox(
-              decoration: BoxDecoration(
-                gradient: LinearGradient(
-                  begin: const Alignment(0.0, -1.0),
-                  end: const Alignment(-0.04, 1.0),
-                  colors: <Color>[Colors.blue.shade500, Colors.blue.shade800],
-                ),
-              ),
-            ),
-          ),
-        ),
-      ),
-    );
-    final RenderObject painter = tester.renderObject(
-      find.descendant(
-        of: find.descendant(
-          of: find.byType(AppBar),
-          matching: find.byType(Stack),
-        ),
-        matching: find.byType(Material)
-      )
-    );
-    await tester.tap(find.byKey(key));
-    expect(painter, paints..save()..translate()..save()..translate()..circle(x: 24.0, y: 28.0));
-  });
-
   testWidgets('AppBar handles loose children 0', (WidgetTester tester) async {
     final GlobalKey key = GlobalKey();
     await tester.pumpWidget(