`simplistic_editor` : Fix keyboard shortcuts on `macOS` (#1684)

* Define performSelector to receive intents from macOS TextInputPlugin and remove local Shortcuts widget to inherit DefaultTextEditingShortcuts

* dart format

simplistic_editor/lib/basic_text_input_client.dart

@@ -111,7 +111,14 @@ class BasicTextInputClientState extends State<BasicTextInputClient>
 
   @override
   void performSelector(String selectorName) {
-    // Will not implement.
+    final Intent? intent = intentForMacOSSelector(selectorName);
+
+    if (intent != null) {
+      final BuildContext? primaryContext = primaryFocus?.context;
+      if (primaryContext != null) {
+        Actions.invoke(primaryContext, intent);
+      }
+    }
   }
 
   @override
@@ -773,28 +780,9 @@ class BasicTextInputClientState extends State<BasicTextInputClient>
     }
   }
 
-  static final Map<ShortcutActivator, Intent> _defaultWebShortcuts =
-      <ShortcutActivator, Intent>{
-    // Activation
-    const SingleActivator(LogicalKeyboardKey.space):
-        const DoNothingAndStopPropagationIntent(),
-
-    // Scrolling
-    const SingleActivator(LogicalKeyboardKey.arrowUp):
-        const DoNothingAndStopPropagationIntent(),
-    const SingleActivator(LogicalKeyboardKey.arrowDown):
-        const DoNothingAndStopPropagationIntent(),
-    const SingleActivator(LogicalKeyboardKey.arrowLeft):
-        const DoNothingAndStopPropagationIntent(),
-    const SingleActivator(LogicalKeyboardKey.arrowRight):
-        const DoNothingAndStopPropagationIntent(),
-  };
-
   @override
   Widget build(BuildContext context) {
-    return Shortcuts(
-      shortcuts: kIsWeb ? _defaultWebShortcuts : <ShortcutActivator, Intent>{},
-      child: Actions(
+    return Actions(
       actions: _actions,
       child: Focus(
         focusNode: widget.focusNode,
@@ -824,8 +812,7 @@ class BasicTextInputClientState extends State<BasicTextInputClient>
                 textAlign: TextAlign.left,
                 textDirection: _textDirection,
                 locale: Localizations.maybeLocaleOf(context),
-                  textHeightBehavior:
-                      DefaultTextHeightBehavior.maybeOf(context),
+                textHeightBehavior: DefaultTextHeightBehavior.maybeOf(context),
                 textWidthBasis: TextWidthBasis.parent,
                 obscuringCharacter: '•',
                 obscureText:
@@ -850,7 +837,6 @@ class BasicTextInputClientState extends State<BasicTextInputClient>
           },
         ),
       ),
-      ),
     );
   }
 }