Revert "fix a Scaffold extendBodyBehindAppBar update bug" (#106396)

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

@@ -875,6 +875,10 @@ class _BodyBuilder extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    if (!extendBody && !extendBodyBehindAppBar) {
+      return body;
+    }
+
     return LayoutBuilder(
       builder: (BuildContext context, BoxConstraints constraints) {
         final _BodyBoxConstraints bodyConstraints = constraints as _BodyBoxConstraints;

packages/flutter/test/material/scaffold_test.dart

@@ -11,39 +11,6 @@ import 'package:flutter_test/flutter_test.dart';
 import '../widgets/semantics_tester.dart';
 
 void main() {
-  // Regression test for https://github.com/flutter/flutter/issues/103741
-  testWidgets('extendBodyBehindAppBar change should not cause the body widget lose state', (WidgetTester tester) async {
-    final ScrollController controller = ScrollController();
-    Widget buildFrame({required bool extendBodyBehindAppBar}) {
-      return MediaQuery(
-        data: const MediaQueryData(),
-        child: Directionality(
-          textDirection: TextDirection.ltr,
-          child: Scaffold(
-            extendBodyBehindAppBar: extendBodyBehindAppBar,
-            resizeToAvoidBottomInset: false,
-            body: SingleChildScrollView(
-              controller: controller,
-              child: const FlutterLogo(
-                size: 1107,
-              ),
-            ),
-          ),
-        ),
-      );
-    }
-
-    await tester.pumpWidget(buildFrame(extendBodyBehindAppBar: true));
-    expect(controller.position.pixels, 0.0);
-
-    controller.jumpTo(100.0);
-    await tester.pump();
-    expect(controller.position.pixels, 100.0);
-
-    await tester.pumpWidget(buildFrame(extendBodyBehindAppBar: false));
-    expect(controller.position.pixels, 100.0);
-  });
-
   testWidgets('Scaffold drawer callback test', (WidgetTester tester) async {
     bool isDrawerOpen = false;
     bool isEndDrawerOpen = false;
@@ -2434,8 +2401,6 @@ void main() {
       '   ancestor was:\n'
       '     Builder\n'
       '   The ancestors of this widget were:\n'
-      '     MediaQuery\n'
-      '     LayoutBuilder\n'
       '     _BodyBuilder\n'
       '     MediaQuery\n'
       '     LayoutId-[<_ScaffoldSlot.body>]\n'

packages/flutter/test/widgets/interactive_viewer_test.dart

@@ -1269,19 +1269,22 @@ void main() {
     testWidgets('LayoutBuilder is only used for InteractiveViewer.builder', (WidgetTester tester) async {
       await tester.pumpWidget(
         MaterialApp(
-          home: Center(
+          home: Scaffold(
+            body: Center(
               child: InteractiveViewer(
                 child: const SizedBox(width: 200.0, height: 200.0),
               ),
             ),
           ),
+        ),
       );
 
       expect(find.byType(LayoutBuilder), findsNothing);
 
       await tester.pumpWidget(
         MaterialApp(
-          home: Center(
+          home: Scaffold(
+            body: Center(
               child: InteractiveViewer.builder(
                 builder: (BuildContext context, Quad viewport) {
                   return const SizedBox(width: 200.0, height: 200.0);
@@ -1289,6 +1292,7 @@ void main() {
               ),
             ),
           ),
+        ),
       );
 
       expect(find.byType(LayoutBuilder), findsOneWidget);

packages/flutter/test/widgets/nested_scroll_view_test.dart

@@ -2360,7 +2360,8 @@ void main() {
   testWidgets('NestedScrollView works well when rebuilding during scheduleWarmUpFrame', (WidgetTester tester) async {
     bool? isScrolled;
     final Widget myApp = MaterialApp(
-      home: StatefulBuilder(
+      home: Scaffold(
+        body: StatefulBuilder(
           builder: (BuildContext context, StateSetter setState) {
             return Focus(
               onFocusChange: (_) => setState( (){} ),
@@ -2390,6 +2391,7 @@ void main() {
             );
           },
         ),
+      ),
     );
 
     await tester.pumpWidget(myApp, Duration.zero, EnginePhase.build);