events: Don't check for stage grabs before sending events to ibus

Prior to the grabs/focus rework in !3420, Wayland grabs were handled
separately from ClutterGrabs. This required explicitly checking for
ClutterGrabs as those were expected to prevent events from reaching
Wayland clients.

Now after !3420, Wayland client grabs also result in ClutterGrabs, which
means that this check causes input events for popups with grabs to not
get sent to ibus anymore. Instead the events are getting sent to the
client directly, which results no ibus support in popups (unless the
client handles that itself by using a different GTK_IM_MODULE).

However due to the changes from !3420 checking for ClutterGrabs is also
no longer necessary and the meta_wayland_text_input_update() focus check
is now sufficient to only forward events to ibus, when the focus is
actually on a Wayland client. So to fix this we can simply remove the
check.

Fixes: 2a584a8f0 ("wayland: Make use of Wayland event grabbing mechanism")
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/3502
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3787>

src/core/events.c

@@ -288,7 +288,6 @@ meta_display_handle_event (MetaDisplay        *display,
 
 #ifdef HAVE_WAYLAND
   if (wayland_text_input &&
-      !has_grab &&
       !meta_compositor_get_current_window_drag (compositor) &&
       meta_wayland_text_input_update (wayland_text_input, event))
     return CLUTTER_EVENT_STOP;