Remove extraneous InheritedWidget (#104676)

When I removed Shortcuts.of and Shortcuts.maybeOf, I forgot to also remove the associated InheritedWidget. This does that.

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

@@ -860,7 +860,7 @@ class Shortcuts extends StatefulWidget {
   /// If this widget was created with [Shortcuts.manager], then
   /// [ShortcutManager.shortcuts] will be used as the source for shortcuts. If
   /// the unnamed constructor is used, this manager will be null, and a
-  /// default-constructed `ShortcutsManager` will be used.
+  /// default-constructed [ShortcutManager] will be used.
   final ShortcutManager? manager;
 
   /// {@template flutter.widgets.shortcuts.shortcuts}
@@ -944,29 +944,11 @@ class _ShortcutsState extends State<Shortcuts> {
       debugLabel: '$Shortcuts',
       canRequestFocus: false,
       onKey: _handleOnKey,
-      child: _ShortcutsMarker(
-        manager: manager,
       child: widget.child,
-      ),
     );
   }
 }
 
-class _ShortcutsMarker extends InheritedWidget {
-  const _ShortcutsMarker({
-    required this.manager,
-    required super.child,
-  })  : assert(manager != null),
-        assert(child != null);
-
-  final ShortcutManager manager;
-
-  @override
-  bool updateShouldNotify(_ShortcutsMarker oldWidget) {
-    return manager != oldWidget.manager;
-  }
-}
-
 /// A widget that provides an uncomplicated mechanism for binding a key
 /// combination to a specific callback.
 ///

packages/flutter/test/material/debug_test.dart

@@ -187,7 +187,6 @@ void main() {
       '     MediaQuery\n'
       '     _MediaQueryFromWindow\n'
       '     _ShortcutRegistrarMarker\n'
-      '     _ShortcutsMarker\n'
       '     Semantics\n'
       '     _FocusMarker\n'
       '     Focus\n'
@@ -200,19 +199,16 @@ void main() {
       '     _ActionsMarker\n'
       '     Actions\n'
       '${kIsWeb
-          ? '     _ShortcutsMarker\n'
-            '     Semantics\n'
+          ? '     Semantics\n'
             '     _FocusMarker\n'
             '     Focus\n'
             '     Shortcuts\n'
            : ''}'
-      '     _ShortcutsMarker\n'
       '     Semantics\n'
       '     _FocusMarker\n'
       '     Focus\n'
       '     Shortcuts\n'
       '     DefaultTextEditingShortcuts\n'
-      '     _ShortcutsMarker\n'
       '     Semantics\n'
       '     _FocusMarker\n'
       '     Focus\n'