fix: properly order out child windows (#29887)

Co-authored-by: Shelley Vohr <shelley.vohr@gmail.com>

shell/browser/native_window_mac.mm

@@ -706,6 +706,15 @@ void ViewDidMoveToSuperview(NSView* self, SEL _cmd) {
     return;
   }
 
+  // Hide all children of the current window before hiding the window.
+  // components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
+  // expects this when window visibility changes.
+  if ([window_ childWindows]) {
+    for (NSWindow* child in [window_ childWindows]) {
+      [child orderOut:nil];
+    }
+  }
+
   // Deattach the window from the parent before.
   if (parent())
     InternalSetParentWindow(parent(), false);