[framework] inline casts on Element.widget getter to improve web performance (#97822)

packages/flutter/lib/src/cupertino/dialog.dart

@@ -916,9 +916,6 @@ class _CupertinoDialogRenderElement extends RenderObjectElement {
   Element? _contentElement;
   Element? _actionsElement;
 
-  @override
-  _CupertinoDialogRenderWidget get widget => super.widget as _CupertinoDialogRenderWidget;
-
   @override
   _RenderCupertinoDialog get renderObject => super.renderObject as _RenderCupertinoDialog;
 
@@ -935,8 +932,9 @@ class _CupertinoDialogRenderElement extends RenderObjectElement {
   @override
   void mount(Element? parent, Object? newSlot) {
     super.mount(parent, newSlot);
-    _contentElement = updateChild(_contentElement, widget.contentSection, _AlertDialogSections.contentSection);
-    _actionsElement = updateChild(_actionsElement, widget.actionsSection, _AlertDialogSections.actionsSection);
+    final _CupertinoDialogRenderWidget dialogRenderWidget = widget as _CupertinoDialogRenderWidget;
+    _contentElement = updateChild(_contentElement, dialogRenderWidget.contentSection, _AlertDialogSections.contentSection);
+    _actionsElement = updateChild(_actionsElement, dialogRenderWidget.actionsSection, _AlertDialogSections.actionsSection);
   }
 
   @override
@@ -957,8 +955,9 @@ class _CupertinoDialogRenderElement extends RenderObjectElement {
   @override
   void update(RenderObjectWidget newWidget) {
     super.update(newWidget);
-    _contentElement = updateChild(_contentElement, widget.contentSection, _AlertDialogSections.contentSection);
-    _actionsElement = updateChild(_actionsElement, widget.actionsSection, _AlertDialogSections.actionsSection);
+    final _CupertinoDialogRenderWidget dialogRenderWidget = widget as _CupertinoDialogRenderWidget;
+    _contentElement = updateChild(_contentElement, dialogRenderWidget.contentSection, _AlertDialogSections.contentSection);
+    _actionsElement = updateChild(_actionsElement, dialogRenderWidget.actionsSection, _AlertDialogSections.actionsSection);
   }
 
   @override

packages/flutter/lib/src/cupertino/text_form_field_row.dart

@@ -274,36 +274,35 @@ class _CupertinoTextFormFieldRowState extends FormFieldState<String> {
   TextEditingController? _controller;
 
   TextEditingController? get _effectiveController =>
-      widget.controller ?? _controller;
+      _cupertinoTextFormFieldRow.controller ?? _controller;
 
-  @override
-  CupertinoTextFormFieldRow get widget =>
+  CupertinoTextFormFieldRow get _cupertinoTextFormFieldRow =>
       super.widget as CupertinoTextFormFieldRow;
 
   @override
   void initState() {
     super.initState();
-    if (widget.controller == null) {
+    if (_cupertinoTextFormFieldRow.controller == null) {
       _controller = TextEditingController(text: widget.initialValue);
     } else {
-      widget.controller!.addListener(_handleControllerChanged);
+      _cupertinoTextFormFieldRow.controller!.addListener(_handleControllerChanged);
     }
   }
 
   @override
   void didUpdateWidget(CupertinoTextFormFieldRow oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (widget.controller != oldWidget.controller) {
+    if (_cupertinoTextFormFieldRow.controller != oldWidget.controller) {
       oldWidget.controller?.removeListener(_handleControllerChanged);
-      widget.controller?.addListener(_handleControllerChanged);
+      _cupertinoTextFormFieldRow.controller?.addListener(_handleControllerChanged);
 
-      if (oldWidget.controller != null && widget.controller == null) {
+      if (oldWidget.controller != null && _cupertinoTextFormFieldRow.controller == null) {
         _controller =
             TextEditingController.fromValue(oldWidget.controller!.value);
       }
 
-      if (widget.controller != null) {
-        setValue(widget.controller!.text);
+      if (_cupertinoTextFormFieldRow.controller != null) {
+        setValue(_cupertinoTextFormFieldRow.controller!.text);
         if (oldWidget.controller == null) {
           _controller = null;
         }
@@ -313,7 +312,7 @@ class _CupertinoTextFormFieldRowState extends FormFieldState<String> {
 
   @override
   void dispose() {
-    widget.controller?.removeListener(_handleControllerChanged);
+    _cupertinoTextFormFieldRow.controller?.removeListener(_handleControllerChanged);
     super.dispose();
   }
 

packages/flutter/lib/src/cupertino/text_selection_toolbar.dart

@@ -522,9 +522,6 @@ class _CupertinoTextSelectionToolbarItemsElement extends RenderObjectElement {
   // repeatedly to remove children.
   final Set<Element> _forgottenChildren = HashSet<Element>();
 
-  @override
-  _CupertinoTextSelectionToolbarItems get widget => super.widget as _CupertinoTextSelectionToolbarItems;
-
   @override
   _RenderCupertinoTextSelectionToolbarItems get renderObject => super.renderObject as _RenderCupertinoTextSelectionToolbarItems;
 
@@ -625,15 +622,16 @@ class _CupertinoTextSelectionToolbarItemsElement extends RenderObjectElement {
   void mount(Element? parent, Object? newSlot) {
     super.mount(parent, newSlot);
     // Mount slotted children.
-    _mountChild(widget.backButton, _CupertinoTextSelectionToolbarItemsSlot.backButton);
-    _mountChild(widget.nextButton, _CupertinoTextSelectionToolbarItemsSlot.nextButton);
-    _mountChild(widget.nextButtonDisabled, _CupertinoTextSelectionToolbarItemsSlot.nextButtonDisabled);
+    final _CupertinoTextSelectionToolbarItems toolbarItems = widget as _CupertinoTextSelectionToolbarItems;
+    _mountChild(toolbarItems.backButton, _CupertinoTextSelectionToolbarItemsSlot.backButton);
+    _mountChild(toolbarItems.nextButton, _CupertinoTextSelectionToolbarItemsSlot.nextButton);
+    _mountChild(toolbarItems.nextButtonDisabled, _CupertinoTextSelectionToolbarItemsSlot.nextButtonDisabled);
 
     // Mount list children.
-    _children = List<Element>.filled(widget.children.length, _NullElement.instance);
+    _children = List<Element>.filled(toolbarItems.children.length, _NullElement.instance);
     Element? previousChild;
     for (int i = 0; i < _children.length; i += 1) {
-      final Element newChild = inflateWidget(widget.children[i], IndexedSlot<Element?>(i, previousChild));
+      final Element newChild = inflateWidget(toolbarItems.children[i], IndexedSlot<Element?>(i, previousChild));
       _children[i] = newChild;
       previousChild = newChild;
     }
@@ -659,12 +657,13 @@ class _CupertinoTextSelectionToolbarItemsElement extends RenderObjectElement {
     assert(widget == newWidget);
 
     // Update slotted children.
-    _mountChild(widget.backButton, _CupertinoTextSelectionToolbarItemsSlot.backButton);
-    _mountChild(widget.nextButton, _CupertinoTextSelectionToolbarItemsSlot.nextButton);
-    _mountChild(widget.nextButtonDisabled, _CupertinoTextSelectionToolbarItemsSlot.nextButtonDisabled);
+    final _CupertinoTextSelectionToolbarItems toolbarItems = widget as _CupertinoTextSelectionToolbarItems;
+    _mountChild(toolbarItems.backButton, _CupertinoTextSelectionToolbarItemsSlot.backButton);
+    _mountChild(toolbarItems.nextButton, _CupertinoTextSelectionToolbarItemsSlot.nextButton);
+    _mountChild(toolbarItems.nextButtonDisabled, _CupertinoTextSelectionToolbarItemsSlot.nextButtonDisabled);
 
     // Update list children.
-    _children = updateChildren(_children, widget.children, forgottenChildren: _forgottenChildren);
+    _children = updateChildren(_children, toolbarItems.children, forgottenChildren: _forgottenChildren);
     _forgottenChildren.clear();
   }
 }

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

@@ -1665,14 +1665,13 @@ class DropdownButtonFormField<T> extends FormField<T> {
 }
 
 class _DropdownButtonFormFieldState<T> extends FormFieldState<T> {
-  @override
-  DropdownButtonFormField<T> get widget => super.widget as DropdownButtonFormField<T>;
 
   @override
   void didChange(T? value) {
     super.didChange(value);
-    assert(widget.onChanged != null);
-    widget.onChanged!(value);
+    final DropdownButtonFormField<T> dropdownButtonFormField = widget as DropdownButtonFormField<T>;
+    assert(dropdownButtonFormField.onChanged != null);
+    dropdownButtonFormField.onChanged!(value);
   }
 
   @override

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

@@ -266,10 +266,9 @@ class TextFormField extends FormField<String> {
 class _TextFormFieldState extends FormFieldState<String> {
   RestorableTextEditingController? _controller;
 
-  TextEditingController get _effectiveController => widget.controller ?? _controller!.value;
+  TextEditingController get _effectiveController => _textFormField.controller ?? _controller!.value;
 
-  @override
-  TextFormField get widget => super.widget as TextFormField;
+  TextFormField get _textFormField => super.widget as TextFormField;
 
   @override
   void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
@@ -300,26 +299,26 @@ class _TextFormFieldState extends FormFieldState<String> {
   @override
   void initState() {
     super.initState();
-    if (widget.controller == null) {
+    if (_textFormField.controller == null) {
       _createLocalController(widget.initialValue != null ? TextEditingValue(text: widget.initialValue!) : null);
     } else {
-      widget.controller!.addListener(_handleControllerChanged);
+      _textFormField.controller!.addListener(_handleControllerChanged);
     }
   }
 
   @override
   void didUpdateWidget(TextFormField oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (widget.controller != oldWidget.controller) {
+    if (_textFormField.controller != oldWidget.controller) {
       oldWidget.controller?.removeListener(_handleControllerChanged);
-      widget.controller?.addListener(_handleControllerChanged);
+      _textFormField.controller?.addListener(_handleControllerChanged);
 
-      if (oldWidget.controller != null && widget.controller == null) {
+      if (oldWidget.controller != null && _textFormField.controller == null) {
         _createLocalController(oldWidget.controller!.value);
       }
 
-      if (widget.controller != null) {
-        setValue(widget.controller!.text);
+      if (_textFormField.controller != null) {
+        setValue(_textFormField.controller!.text);
         if (oldWidget.controller == null) {
           unregisterFromRestoration(_controller!);
           _controller!.dispose();
@@ -331,7 +330,7 @@ class _TextFormFieldState extends FormFieldState<String> {
 
   @override
   void dispose() {
-    widget.controller?.removeListener(_handleControllerChanged);
+    _textFormField.controller?.removeListener(_handleControllerChanged);
     _controller?.dispose();
     super.dispose();
   }

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

@@ -3131,12 +3131,9 @@ class Offstage extends SingleChildRenderObjectWidget {
 class _OffstageElement extends SingleChildRenderObjectElement {
   _OffstageElement(Offstage widget) : super(widget);
 
-  @override
-  Offstage get widget => super.widget as Offstage;
-
   @override
   void debugVisitOnstageChildren(ElementVisitor visitor) {
-    if (!widget.offstage)
+    if (!(widget as Offstage).offstage)
       super.debugVisitOnstageChildren(visitor);
   }
 }

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

@@ -1138,9 +1138,6 @@ class RenderObjectToWidgetElement<T extends RenderObject> extends RootRenderObje
   /// the render tree, call [RenderObjectToWidgetAdapter.attachToRenderTree].
   RenderObjectToWidgetElement(RenderObjectToWidgetAdapter<T> widget) : super(widget);
 
-  @override
-  RenderObjectToWidgetAdapter<T> get widget => super.widget as RenderObjectToWidgetAdapter<T>;
-
   Element? _child;
 
   static const Object _rootChildSlot = Object();
@@ -1193,7 +1190,7 @@ class RenderObjectToWidgetElement<T extends RenderObject> extends RootRenderObje
   @pragma('vm:notify-debugger-on-exception')
   void _rebuild() {
     try {
-      _child = updateChild(_child, widget.child, _rootChildSlot);
+      _child = updateChild(_child, (widget as RenderObjectToWidgetAdapter<T>).child, _rootChildSlot);
     } catch (exception, stack) {
       final FlutterErrorDetails details = FlutterErrorDetails(
         exception: exception,

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

@@ -184,9 +184,6 @@ class InheritedModelElement<T> extends InheritedElement {
   /// Creates an element that uses the given widget as its configuration.
   InheritedModelElement(InheritedModel<T> widget) : super(widget);
 
-  @override
-  InheritedModel<T> get widget => super.widget as InheritedModel<T>;
-
   @override
   void updateDependencies(Element dependent, Object? aspect) {
     final Set<T>? dependencies = getDependencies(dependent) as Set<T>?;
@@ -206,7 +203,7 @@ class InheritedModelElement<T> extends InheritedElement {
     final Set<T>? dependencies = getDependencies(dependent) as Set<T>?;
     if (dependencies == null)
       return;
-    if (dependencies.isEmpty || widget.updateShouldNotifyDependent(oldWidget, dependencies))
+    if (dependencies.isEmpty || (widget as InheritedModel<T>).updateShouldNotifyDependent(oldWidget, dependencies))
       dependent.didChangeDependencies();
   }
 }

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

@@ -95,14 +95,11 @@ class _InheritedNotifierElement<T extends Listenable> extends InheritedElement {
     widget.notifier?.addListener(_handleUpdate);
   }
 
-  @override
-  InheritedNotifier<T> get widget => super.widget as InheritedNotifier<T>;
-
   bool _dirty = false;
 
   @override
   void update(InheritedNotifier<T> newWidget) {
-    final T? oldNotifier = widget.notifier;
+    final T? oldNotifier = (widget as InheritedNotifier<T>).notifier;
     final T? newNotifier = newWidget.notifier;
     if (oldNotifier != newNotifier) {
       oldNotifier?.removeListener(_handleUpdate);
@@ -114,7 +111,7 @@ class _InheritedNotifierElement<T extends Listenable> extends InheritedElement {
   @override
   Widget build() {
     if (_dirty)
-      notifyClients(widget);
+      notifyClients(widget as InheritedNotifier<T>);
     return super.build();
   }
 
@@ -131,7 +128,7 @@ class _InheritedNotifierElement<T extends Listenable> extends InheritedElement {
 
   @override
   void unmount() {
-    widget.notifier?.removeListener(_handleUpdate);
+    (widget as InheritedNotifier<T>).notifier?.removeListener(_handleUpdate);
     super.unmount();
   }
 }

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

@@ -57,9 +57,6 @@ abstract class ConstrainedLayoutBuilder<ConstraintType extends Constraints> exte
 class _LayoutBuilderElement<ConstraintType extends Constraints> extends RenderObjectElement {
   _LayoutBuilderElement(ConstrainedLayoutBuilder<ConstraintType> widget) : super(widget);
 
-  @override
-  ConstrainedLayoutBuilder<ConstraintType> get widget => super.widget as ConstrainedLayoutBuilder<ConstraintType>;
-
   @override
   RenderConstrainedLayoutBuilder<ConstraintType, RenderObject> get renderObject => super.renderObject as RenderConstrainedLayoutBuilder<ConstraintType, RenderObject>;
 
@@ -119,7 +116,7 @@ class _LayoutBuilderElement<ConstraintType extends Constraints> extends RenderOb
     void layoutCallback() {
       Widget built;
       try {
-        built = widget.builder(this, constraints);
+        built = (widget as ConstrainedLayoutBuilder<ConstraintType>).builder(this, constraints);
         debugWidgetBuilderValue(widget, built);
       } catch (e, stack) {
         built = ErrorWidget.builder(

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

@@ -818,9 +818,6 @@ class ListWheelElement extends RenderObjectElement implements ListWheelChildMana
   /// Creates an element that lazily builds children for the given widget.
   ListWheelElement(ListWheelViewport widget) : super(widget);
 
-  @override
-  ListWheelViewport get widget => super.widget as ListWheelViewport;
-
   @override
   RenderListWheelViewport get renderObject => super.renderObject as RenderListWheelViewport;
 
@@ -840,7 +837,7 @@ class ListWheelElement extends RenderObjectElement implements ListWheelChildMana
 
   @override
   void update(ListWheelViewport newWidget) {
-    final ListWheelViewport oldWidget = widget;
+    final ListWheelViewport oldWidget = widget as ListWheelViewport;
     super.update(newWidget);
     final ListWheelChildDelegate newDelegate = newWidget.childDelegate;
     final ListWheelChildDelegate oldDelegate = oldWidget.childDelegate;
@@ -852,7 +849,7 @@ class ListWheelElement extends RenderObjectElement implements ListWheelChildMana
   }
 
   @override
-  int? get childCount => widget.childDelegate.estimatedChildCount;
+  int? get childCount => (widget as ListWheelViewport).childDelegate.estimatedChildCount;
 
   @override
   void performRebuild() {
@@ -880,7 +877,7 @@ class ListWheelElement extends RenderObjectElement implements ListWheelChildMana
   /// will be cached. However when the element is rebuilt, the cache will be
   /// cleared.
   Widget? retrieveWidget(int index) {
-    return _childWidgets.putIfAbsent(index, () => widget.childDelegate.build(this, index));
+    return _childWidgets.putIfAbsent(index, () => (widget as ListWheelViewport).childDelegate.build(this, index));
   }
 
   @override

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

@@ -62,7 +62,7 @@ abstract class Notification {
   @mustCallSuper
   bool visitAncestor(Element element) {
     if (element is StatelessElement) {
-      final StatelessWidget widget = element.widget;
+      final Widget widget = element.widget;
       if (widget is NotificationListener<Notification>) {
         if (widget._dispatch(this, element)) // that function checks the type dynamically
           return false;

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

@@ -578,16 +578,14 @@ class _Theatre extends MultiChildRenderObjectWidget {
 class _TheatreElement extends MultiChildRenderObjectElement {
   _TheatreElement(_Theatre widget) : super(widget);
 
-  @override
-  _Theatre get widget => super.widget as _Theatre;
-
   @override
   _RenderTheatre get renderObject => super.renderObject as _RenderTheatre;
 
   @override
   void debugVisitOnstageChildren(ElementVisitor visitor) {
-    assert(children.length >= widget.skipCount);
-    children.skip(widget.skipCount).forEach(visitor);
+    final _Theatre theatre = widget as _Theatre;
+    assert(children.length >= theatre.skipCount);
+    children.skip(theatre.skipCount).forEach(visitor);
   }
 }
 

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

@@ -1126,15 +1126,12 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
 
   final bool _replaceMovedChildren;
 
-  @override
-  SliverMultiBoxAdaptorWidget get widget => super.widget as SliverMultiBoxAdaptorWidget;
-
   @override
   RenderSliverMultiBoxAdaptor get renderObject => super.renderObject as RenderSliverMultiBoxAdaptor;
 
   @override
   void update(covariant SliverMultiBoxAdaptorWidget newWidget) {
-    final SliverMultiBoxAdaptorWidget oldWidget = widget;
+    final SliverMultiBoxAdaptorWidget oldWidget = widget as SliverMultiBoxAdaptorWidget;
     super.update(newWidget);
     final SliverChildDelegate newDelegate = newWidget.delegate;
     final SliverChildDelegate oldDelegate = oldWidget.delegate;
@@ -1155,6 +1152,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
     try {
       final SplayTreeMap<int, Element?> newChildren = SplayTreeMap<int, Element?>();
       final Map<int, double> indexToLayoutOffset = HashMap<int, double>();
+      final SliverMultiBoxAdaptorWidget adaptorWidget = widget as SliverMultiBoxAdaptorWidget;
       void processElement(int index) {
         _currentlyUpdatingChildIndex = index;
         if (_childElements[index] != null && _childElements[index] != newChildren[index]) {
@@ -1162,7 +1160,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
           _childElements[index] = updateChild(_childElements[index], null, index);
           childrenUpdated = true;
         }
-        final Element? newChild = updateChild(newChildren[index], _build(index), index);
+        final Element? newChild = updateChild(newChildren[index], _build(index, adaptorWidget), index);
         if (newChild != null) {
           childrenUpdated = childrenUpdated || _childElements[index] != newChild;
           _childElements[index] = newChild;
@@ -1181,7 +1179,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
       }
       for (final int index in _childElements.keys.toList()) {
         final Key? key = _childElements[index]!.widget.key;
-        final int? newIndex = key == null ? null : widget.delegate.findIndexByKey(key);
+        final int? newIndex = key == null ? null : adaptorWidget.delegate.findIndexByKey(key);
         final SliverMultiBoxAdaptorParentData? childParentData =
           _childElements[index]!.renderObject?.parentData as SliverMultiBoxAdaptorParentData?;
 
@@ -1228,7 +1226,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
     }
   }
 
-  Widget? _build(int index) {
+  Widget? _build(int index, SliverMultiBoxAdaptorWidget widget) {
     return widget.delegate.build(this, index);
   }
 
@@ -1241,8 +1239,9 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
       _currentBeforeChild = insertFirst ? null : (_childElements[index-1]!.renderObject as RenderBox?);
       Element? newChild;
       try {
+        final SliverMultiBoxAdaptorWidget adaptorWidget = widget as SliverMultiBoxAdaptorWidget;
         _currentlyUpdatingChildIndex = index;
-        newChild = updateChild(_childElements[index], _build(index), index);
+        newChild = updateChild(_childElements[index], _build(index, adaptorWidget), index);
       } finally {
         _currentlyUpdatingChildIndex = null;
       }
@@ -1321,7 +1320,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
     final int? childCount = estimatedChildCount;
     if (childCount == null)
       return double.infinity;
-    return widget.estimateMaxScrollOffset(
+    return (widget as SliverMultiBoxAdaptorWidget).estimateMaxScrollOffset(
       constraints,
       firstIndex!,
       lastIndex!,
@@ -1345,7 +1344,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
   /// See also:
   ///
   ///  * [SliverChildDelegate.estimatedChildCount], to which this getter defers.
-  int? get estimatedChildCount => widget.delegate.estimatedChildCount;
+  int? get estimatedChildCount => (widget as SliverMultiBoxAdaptorWidget).delegate.estimatedChildCount;
 
   @override
   int get childCount {
@@ -1358,10 +1357,11 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
       // manually.
       int lo = 0;
       int hi = 1;
+      final SliverMultiBoxAdaptorWidget adaptorWidget = widget as SliverMultiBoxAdaptorWidget;
       const int max = kIsWeb
         ? 9007199254740992 // max safe integer on JS (from 0 to this number x != x+1)
         : ((1 << 63) - 1);
-      while (_build(hi - 1) != null) {
+      while (_build(hi - 1, adaptorWidget) != null) {
         lo = hi - 1;
         if (hi < max ~/ 2) {
           hi *= 2;
@@ -1369,7 +1369,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
           hi = max;
         } else {
           throw FlutterError(
-            'Could not find the number of children in ${widget.delegate}.\n'
+            'Could not find the number of children in ${adaptorWidget.delegate}.\n'
             "The childCount getter was called (implying that the delegate's builder returned null "
             'for a positive index), but even building the child with index $hi (the maximum '
             'possible integer) did not return null. Consider implementing childCount to avoid '
@@ -1379,7 +1379,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
       }
       while (hi - lo > 1) {
         final int mid = (hi - lo) ~/ 2 + lo;
-        if (_build(mid - 1) == null) {
+        if (_build(mid - 1, adaptorWidget) == null) {
           hi = mid;
         } else {
           lo = mid;
@@ -1400,7 +1400,7 @@ class SliverMultiBoxAdaptorElement extends RenderObjectElement implements Render
     assert(debugAssertChildListLocked());
     final int firstIndex = _childElements.firstKey() ?? 0;
     final int lastIndex = _childElements.lastKey() ?? 0;
-    widget.delegate.didFinishLayout(firstIndex, lastIndex);
+    (widget as SliverMultiBoxAdaptorWidget).delegate.didFinishLayout(firstIndex, lastIndex);
   }
 
   int? _currentlyUpdatingChildIndex;
@@ -1694,12 +1694,9 @@ class SliverOffstage extends SingleChildRenderObjectWidget {
 class _SliverOffstageElement extends SingleChildRenderObjectElement {
   _SliverOffstageElement(SliverOffstage widget) : super(widget);
 
-  @override
-  SliverOffstage get widget => super.widget as SliverOffstage;
-
   @override
   void debugVisitOnstageChildren(ElementVisitor visitor) {
-    if (!widget.offstage)
+    if (!(widget as SliverOffstage).offstage)
       super.debugVisitOnstageChildren(visitor);
   }
 }

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

@@ -254,9 +254,6 @@ class _SliverPersistentHeaderElement extends RenderObjectElement {
 
   final bool floating;
 
-  @override
-  _SliverPersistentHeaderRenderObjectWidget get widget => super.widget as _SliverPersistentHeaderRenderObjectWidget;
-
   @override
   _RenderSliverPersistentHeaderForWidgetsMixin get renderObject => super.renderObject as _RenderSliverPersistentHeaderForWidgetsMixin;
 
@@ -274,7 +271,7 @@ class _SliverPersistentHeaderElement extends RenderObjectElement {
 
   @override
   void update(_SliverPersistentHeaderRenderObjectWidget newWidget) {
-    final _SliverPersistentHeaderRenderObjectWidget oldWidget = widget;
+    final _SliverPersistentHeaderRenderObjectWidget oldWidget = widget as _SliverPersistentHeaderRenderObjectWidget;
     super.update(newWidget);
     final SliverPersistentHeaderDelegate newDelegate = newWidget.delegate;
     final SliverPersistentHeaderDelegate oldDelegate = oldWidget.delegate;
@@ -293,15 +290,16 @@ class _SliverPersistentHeaderElement extends RenderObjectElement {
 
   void _build(double shrinkOffset, bool overlapsContent) {
     owner!.buildScope(this, () {
+      final _SliverPersistentHeaderRenderObjectWidget sliverPersistentHeaderRenderObjectWidget = widget as _SliverPersistentHeaderRenderObjectWidget;
       child = updateChild(
         child,
         floating
-          ? _FloatingHeader(child: widget.delegate.build(
+          ? _FloatingHeader(child: sliverPersistentHeaderRenderObjectWidget.delegate.build(
             this,
             shrinkOffset,
             overlapsContent
           ))
-          : widget.delegate.build(this, shrinkOffset, overlapsContent),
+          : sliverPersistentHeaderRenderObjectWidget.delegate.build(this, shrinkOffset, overlapsContent),
         null,
       );
     });
@@ -371,10 +369,10 @@ mixin _RenderSliverPersistentHeaderForWidgetsMixin on RenderSliverPersistentHead
   _SliverPersistentHeaderElement? _element;
 
   @override
-  double get minExtent => _element!.widget.delegate.minExtent;
+  double get minExtent => (_element!.widget as _SliverPersistentHeaderRenderObjectWidget).delegate.minExtent;
 
   @override
-  double get maxExtent => _element!.widget.delegate.maxExtent;
+  double get maxExtent => (_element!.widget as _SliverPersistentHeaderRenderObjectWidget).delegate.maxExtent;
 
   @override
   void updateChild(double shrinkOffset, bool overlapsContent) {

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

@@ -62,9 +62,6 @@ class SliverPrototypeExtentList extends SliverMultiBoxAdaptorWidget {
 class _SliverPrototypeExtentListElement extends SliverMultiBoxAdaptorElement {
   _SliverPrototypeExtentListElement(SliverPrototypeExtentList widget) : super(widget);
 
-  @override
-  SliverPrototypeExtentList get widget => super.widget as SliverPrototypeExtentList;
-
   @override
   _RenderSliverPrototypeExtentList get renderObject => super.renderObject as _RenderSliverPrototypeExtentList;
 
@@ -113,14 +110,14 @@ class _SliverPrototypeExtentListElement extends SliverMultiBoxAdaptorElement {
   @override
   void mount(Element? parent, Object? newSlot) {
     super.mount(parent, newSlot);
-    _prototype = updateChild(_prototype, widget.prototypeItem, _prototypeSlot);
+    _prototype = updateChild(_prototype, (widget as SliverPrototypeExtentList).prototypeItem, _prototypeSlot);
   }
 
   @override
   void update(SliverPrototypeExtentList newWidget) {
     super.update(newWidget);
     assert(widget == newWidget);
-    _prototype = updateChild(_prototype, widget.prototypeItem, _prototypeSlot);
+    _prototype = updateChild(_prototype, (widget as SliverPrototypeExtentList).prototypeItem, _prototypeSlot);
   }
 }
 

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

@@ -191,9 +191,6 @@ class SlottedRenderObjectElement<S> extends RenderObjectElement {
 
   final Map<S, Element> _slotToChild = <S, Element>{};
 
-  @override
-  SlottedMultiChildRenderObjectWidgetMixin<S> get widget => super.widget as SlottedMultiChildRenderObjectWidgetMixin<S>;
-
   @override
   SlottedContainerRenderObjectMixin<S> get renderObject => super.renderObject as SlottedContainerRenderObjectMixin<S>;
 
@@ -227,14 +224,15 @@ class SlottedRenderObjectElement<S> extends RenderObjectElement {
   List<S>? _debugPreviousSlots;
 
   void _updateChildren() {
+    final SlottedMultiChildRenderObjectWidgetMixin<S> slottedMultiChildRenderObjectWidgetMixin = widget as SlottedMultiChildRenderObjectWidgetMixin<S>;
     assert(() {
-      _debugPreviousSlots ??= widget.slots.toList();
-      return listEquals(_debugPreviousSlots, widget.slots.toList());
+      _debugPreviousSlots ??= slottedMultiChildRenderObjectWidgetMixin.slots.toList();
+      return listEquals(_debugPreviousSlots, slottedMultiChildRenderObjectWidgetMixin.slots.toList());
     }(), '${widget.runtimeType}.slots must not change.');
-    assert(widget.slots.toSet().length == widget.slots.length, 'slots must be unique');
+    assert(slottedMultiChildRenderObjectWidgetMixin.slots.toSet().length == slottedMultiChildRenderObjectWidgetMixin.slots.length, 'slots must be unique');
 
-    for (final S slot in widget.slots) {
-      _updateChild(widget.childForSlot(slot), slot);
+    for (final S slot in slottedMultiChildRenderObjectWidgetMixin.slots) {
+      _updateChild(slottedMultiChildRenderObjectWidgetMixin.childForSlot(slot), slot);
     }
   }
 

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

@@ -284,9 +284,6 @@ class Table extends RenderObjectWidget {
 class _TableElement extends RenderObjectElement {
   _TableElement(Table widget) : super(widget);
 
-  @override
-  Table get widget => super.widget as Table;
-
   @override
   RenderTable get renderObject => super.renderObject as RenderTable;
 
@@ -300,7 +297,7 @@ class _TableElement extends RenderObjectElement {
     _doingMountOrUpdate = true;
     super.mount(parent, newSlot);
     int rowIndex = -1;
-    _children = widget.children.map<_TableElementRow>((TableRow row) {
+    _children = (widget as Table).children.map<_TableElementRow>((TableRow row) {
       int columnIndex = 0;
       rowIndex += 1;
       return _TableElementRow(

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

@@ -214,9 +214,6 @@ class _ViewportElement extends MultiChildRenderObjectElement {
   bool _doingMountOrUpdate = false;
   int? _centerSlotIndex;
 
-  @override
-  Viewport get widget => super.widget as Viewport;
-
   @override
   RenderViewport get renderObject => super.renderObject as RenderViewport;
 
@@ -242,10 +239,11 @@ class _ViewportElement extends MultiChildRenderObjectElement {
 
   void _updateCenter() {
     // TODO(ianh): cache the keys to make this faster
-    if (widget.center != null) {
+    final Viewport viewport = widget as Viewport;
+    if (viewport.center != null) {
       int elementIndex = 0;
       for (final Element e in children) {
-        if (e.widget.key == widget.center) {
+        if (e.widget.key == viewport.center) {
           renderObject.center = e.renderObject as RenderSliver?;
           break;
         }

packages/flutter_test/lib/src/widget_tester.dart

@@ -709,7 +709,7 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
       'therefore no restoration data has been collected to restore from. Did you forget to wrap '
       'your widget tree in a RootRestorationScope?',
     );
-    final Widget widget = (binding.renderViewElement! as RenderObjectToWidgetElement<RenderObject>).widget.child!;
+    final Widget widget = ((binding.renderViewElement! as RenderObjectToWidgetElement<RenderObject>).widget as RenderObjectToWidgetAdapter<RenderObject>).child!;
     final TestRestorationData restorationData = binding.restorationManager.restorationData;
     runApp(Container(key: UniqueKey()));
     await pump();