Fix typos in keyboard code (#78464)

packages/flutter/lib/src/services/raw_keyboard.dart

@@ -228,11 +228,11 @@ abstract class RawKeyEventData {
   String get keyLabel;
 
   /// Whether a key down event, and likewise its accompanying key up event,
-  /// should be disapatched.
+  /// should be dispatched.
   ///
   /// Certain events on some platforms should not be dispatched to listeners
   /// according to Flutter's event model. For example, on macOS, Fn keys are
-  /// skipped to be consistant with other platform. On Win32, events dispatched
+  /// skipped to be consistent with other platform. On Win32, events dispatched
   /// for IME (`VK_PROCESSKEY`) are also skipped.
   ///
   /// This method will be called upon every down events. By default, this method
@@ -284,7 +284,6 @@ abstract class RawKeyEvent with Diagnosticable {
     final RawKeyEventData data;
     String? character;
 
-    final String keymap = message['keymap'] as String;
     if (kIsWeb) {
       final String? key = message['key'] as String?;
       data = RawKeyEventDataWeb(
@@ -296,6 +295,7 @@ abstract class RawKeyEvent with Diagnosticable {
         character = key;
       }
     } else {
+      final String keymap = message['keymap'] as String;
       switch (keymap) {
         case 'android':
           data = RawKeyEventDataAndroid(