Correct GtkKeyHelper key codes for the Meta key (#69576)

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

@@ -345,7 +345,7 @@ class GtkKeyHelper with KeyHelper {
   /// test whether one of the Meta(SUPER) modifier keys is pressed.
   ///
   /// {@macro flutter.services.GtkKeyHelper.modifierShift}
-  static const int modifierMeta = 1 << 28;
+  static const int modifierMeta = 1 << 26;
 
   int _mergeModifiers({required int modifiers, required int keyCode, required bool isDown}) {
     // GTK Key codes for modifier keys.
@@ -355,10 +355,10 @@ class GtkKeyHelper with KeyHelper {
     const int controlRightKeyCode = 0xffe4;
     const int capsLockKeyCode = 0xffe5;
     const int shiftLockKeyCode = 0xffe6;
-    const int metaLeftKeyCode = 0xffe7;
-    const int metaRightKeyCode = 0xffe8;
     const int altLeftKeyCode = 0xffe9;
     const int altRightKeyCode = 0xffea;
+    const int metaLeftKeyCode = 0xffeb;
+    const int metaRightKeyCode = 0xffec;
     const int numLockKeyCode = 0xff7f;
 
     // On GTK, the "modifiers" bitfield is the state as it is BEFORE this event

packages/flutter/test/services/raw_keyboard_test.dart

@@ -1594,7 +1594,7 @@ void main() {
         case GtkKeyHelper.modifierControl:
           return isLeft ? 65507 : 65508;
         case GtkKeyHelper.modifierMeta:
-          return isLeft ? 65511 : 65512;
+          return isLeft ? 65515 : 65516;
         case GtkKeyHelper.modifierMod2:
           return 65407;
         case GtkKeyHelper.modifierCapsLock: