Convert menus to use OverlayPortal (#130534)

## Description

This converts the `MenuAnchor` class to use `OverlayPortal` instead of directly using the overlay.

## Related Issues
 - Fixes https://github.com/flutter/flutter/issues/124830

## Tests
 - No tests yet (hence it is a draft)

examples/api/lib/material/menu_anchor/menu_anchor.2.dart

@@ -6,11 +6,12 @@ import 'package:flutter/material.dart';
 
 /// Flutter code sample for [MenuAnchor].
 
-// This is the type used by the menu below.
-enum SampleItem { itemOne, itemTwo, itemThree }
 
 void main() => runApp(const MenuAnchorApp());
 
+// This is the type used by the menu below.
+enum SampleItem { itemOne, itemTwo, itemThree }
+
 class MenuAnchorApp extends StatelessWidget {
   const MenuAnchorApp({super.key});
 
@@ -36,7 +37,10 @@ class _MenuAnchorExampleState extends State<MenuAnchorExample> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: AppBar(title: const Text('MenuAnchorButton')),
+      appBar: AppBar(
+        title: const Text('MenuAnchorButton'),
+        backgroundColor: Theme.of(context).primaryColorLight,
+      ),
       body: Center(
         child: MenuAnchor(
           builder:

examples/api/test/material/menu_anchor/menu_anchor.1_test.dart

@@ -51,7 +51,18 @@ void main() {
 
     expect(find.text('Background Color'), findsOneWidget);
 
+    // Focusing the background color item with the keyboard caused the submenu
+    // to open. Tapping it should cause it to close.
     await tester.tap(find.text('Background Color'));
+    await tester.pump();
+    await tester.pumpAndSettle();
+
+    expect(find.text(example.MenuEntry.colorRed.label), findsNothing);
+    expect(find.text(example.MenuEntry.colorGreen.label), findsNothing);
+    expect(find.text(example.MenuEntry.colorBlue.label), findsNothing);
+
+    await tester.tap(find.text('Background Color'));
+    await tester.pump();
     await tester.pumpAndSettle();
 
     expect(find.text(example.MenuEntry.colorRed.label), findsOneWidget);

packages/flutter/lib/src/rendering/viewport_offset.dart

@@ -257,7 +257,7 @@ abstract class ViewportOffset extends ChangeNotifier {
   /// Whether a viewport is allowed to change [pixels] implicitly to respond to
   /// a call to [RenderObject.showOnScreen].
   ///
-  /// [RenderObject.showOnScreen] is for example used to bring a text field
+  /// [RenderObject.showOnScreen] is, for example, used to bring a text field
   /// fully on screen after it has received focus. This property controls
   /// whether the viewport associated with this offset is allowed to change the
   /// offset's [pixels] value to fulfill such a request.

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

@@ -189,7 +189,8 @@ abstract class FocusTraversalPolicy with Diagnosticable {
   }) {
     node.requestFocus();
     Scrollable.ensureVisible(
-      node.context!, alignment: alignment ?? 1.0,
+      node.context!,
+      alignment: alignment ?? 1,
       alignmentPolicy: alignmentPolicy ?? ScrollPositionAlignmentPolicy.explicit,
       duration: duration ?? Duration.zero,
       curve: curve ?? Curves.ease,
@@ -467,7 +468,6 @@ abstract class FocusTraversalPolicy with Diagnosticable {
       groups[key]!.members.addAll(sortedMembers);
     }
 
-
     // Traverse the group tree, adding the children of members in the order they
     // appear in the member lists.
     final List<FocusNode> sortedDescendants = <FocusNode>[];
@@ -504,9 +504,9 @@ abstract class FocusTraversalPolicy with Diagnosticable {
         // The scope.traversalDescendants will not contain currentNode if it
         // skips traversal or not focusable.
         assert(
-         difference.length == 1 && difference.contains(currentNode),
-         'Sorted descendants contains different nodes than FocusScopeNode.traversalDescendants would. '
-         'These are the different nodes: ${difference.where((FocusNode node) => node != currentNode)}',
+         difference.isEmpty || (difference.length == 1 && difference.contains(currentNode)),
+         'Difference between sorted descendants and FocusScopeNode.traversalDescendants contains '
+         'something other than the current skipped node. This is the difference: $difference',
         );
         return true;
       }

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

@@ -1414,7 +1414,7 @@ class OverlayPortalController {
       : _zOrderIndex != null;
   }
 
-  /// Conventience method for toggling the current [isShowing] status.
+  /// Convenience method for toggling the current [isShowing] status.
   ///
   /// This method should typically not be called while the widget tree is being
   /// rebuilt.

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

@@ -795,9 +795,13 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
     Curve curve = Curves.ease,
     ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicit,
     RenderObject? targetRenderObject,
-  }) {
+  }) async {
     assert(object.attached);
-    final RenderAbstractViewport viewport = RenderAbstractViewport.of(object);
+    final RenderAbstractViewport? viewport = RenderAbstractViewport.maybeOf(object);
+    // If no viewport is found, return.
+    if (viewport == null) {
+      return;
+    }
 
     Rect? targetRect;
     if (targetRenderObject != null && targetRenderObject != object) {
@@ -842,12 +846,12 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
     }
 
     if (target == pixels) {
-      return Future<void>.value();
+      return;
     }
 
     if (duration == Duration.zero) {
       jumpTo(target);
-      return Future<void>.value();
+      return;
     }
 
     return animateTo(target, duration: duration, curve: curve);

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

@@ -461,11 +461,12 @@ class Scrollable extends StatefulWidget {
   }) {
     final List<Future<void>> futures = <Future<void>>[];
 
-    // The `targetRenderObject` is used to record the first target renderObject.
-    // If there are multiple scrollable widgets nested, we should let
-    // the `targetRenderObject` as visible as possible to improve the user experience.
-    // Otherwise, let the outer renderObject as visible as possible maybe cause
-    // the `targetRenderObject` invisible.
+    // The targetRenderObject is used to record the first target renderObject.
+    // If there are multiple scrollable widgets nested, the targetRenderObject
+    // is made to be as visible as possible to improve the user experience. If
+    // the targetRenderObject is already visible, then let the outer
+    // renderObject be as visible as possible.
+    //
     // Also see https://github.com/flutter/flutter/issues/65100
     RenderObject? targetRenderObject;
     ScrollableState? scrollable = Scrollable.maybeOf(context);
@@ -481,7 +482,7 @@ class Scrollable extends StatefulWidget {
       );
       futures.addAll(newFutures);
 
-      targetRenderObject = targetRenderObject ?? context.findRenderObject();
+      targetRenderObject ??= context.findRenderObject();
       context = scrollable.context;
       scrollable = Scrollable.maybeOf(context);
     }

packages/flutter/test/material/dropdown_menu_test.dart

@@ -61,7 +61,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.widgetWithText(TextButton, TestMenu.mainMenu0.label),
       matching: find.byType(Material),
-    ).last;
+    ).at(1);
     Material material = tester.widget<Material>(menuMaterial);
     expect(material.color, themeData.colorScheme.surface);
     expect(material.shadowColor, themeData.colorScheme.shadow);
@@ -143,7 +143,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.byType(SingleChildScrollView),
       matching: find.byType(Material),
-    );
+    ).first;
     final Size menuSize = tester.getSize(menuMaterial);
     expect(menuSize, const Size(180.0, 304.0));
 
@@ -161,7 +161,7 @@ void main() {
     final Finder updatedMenu = find.ancestor(
       of: find.byType(SingleChildScrollView),
       matching: find.byType(Material),
-    );
+    ).first;
     final double updatedMenuWidth = tester.getSize(updatedMenu).width;
     expect(updatedMenuWidth, 200.0);
   });
@@ -192,7 +192,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.byType(SingleChildScrollView),
       matching: find.byType(Material),
-    );
+    ).first;
     final double menuWidth = tester.getSize(menuMaterial).width;
     expect(menuWidth, closeTo(180.5, 0.1));
 
@@ -210,7 +210,7 @@ void main() {
     final Finder updatedMenu = find.ancestor(
       of: find.byType(SingleChildScrollView),
       matching: find.byType(Material),
-    );
+    ).first;
     final double updatedMenuWidth = tester.getSize(updatedMenu).width;
     expect(updatedMenuWidth, 200.0);
   });
@@ -644,8 +644,8 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.widgetWithText(MenuItemButton, TestMenu.mainMenu0.label),
       matching: find.byType(Material),
-    ).last;
-    expect(menuMaterial, findsOneWidget);
+    );
+    expect(menuMaterial, findsNWidgets(3));
 
     // didChangeMetrics
     tester.view.physicalSize = const Size(700.0, 700.0);

packages/flutter/test/material/dropdown_menu_theme_test.dart

@@ -80,7 +80,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.widgetWithText(TextButton, 'Item 0'),
       matching: find.byType(Material),
-    ).last;
+    ).at(1);
     Material material = tester.widget<Material>(menuMaterial);
     expect(material.color, themeData.colorScheme.surface);
     expect(material.shadowColor, themeData.colorScheme.shadow);
@@ -159,7 +159,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.widgetWithText(TextButton, 'Item 0'),
       matching: find.byType(Material),
-    ).last;
+    ).at(1);
     Material material = tester.widget<Material>(menuMaterial);
     expect(material.color, Colors.grey);
     expect(material.shadowColor, Colors.brown);
@@ -262,7 +262,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.widgetWithText(TextButton, 'Item 0'),
       matching: find.byType(Material),
-    ).last;
+    ).at(1);
     Material material = tester.widget<Material>(menuMaterial);
     expect(material.color, Colors.yellow);
     expect(material.shadowColor, Colors.green);
@@ -383,7 +383,7 @@ void main() {
     final Finder menuMaterial = find.ancestor(
       of: find.widgetWithText(TextButton, 'Item 0'),
       matching: find.byType(Material),
-    ).last;
+    ).at(1);
     Material material = tester.widget<Material>(menuMaterial);
     expect(material.color, Colors.limeAccent);
     expect(material.shadowColor, Colors.deepOrangeAccent);