The current implementation of the XdgSurface v6 protocol does not check
if the window changed before calling meta_window_wayland_move_resize().
The problem with this approach is that calling this function is a costly
operation since we enter the compositor side. In GNOME Shell case, it is
in JavaScript, which triggers a GJS trampoline. Calling this function on
every mouse movement is naturally as terrible as it could be - and is
exactly what happens now.
This commit adds the necessary checks to only call move_resize() when
the window actually changed, or when it needs to be updated.
https://bugzilla.gnome.org/show_bug.cgi?id=780292
Issue: #78