Popups with relative position x < 0 && y < 0 are not shown (after move-to-rect)

When tooltip is created with x < 0 and y < 0 (which is correct, for instance when we show tooltip of something outside of latest/topmost popup window) Gtk silently fails to map that window. The code says:

  /* Don't map crazy temp that GTK+ uses for internal X11 shenanigans. */
  if (window->window_type == GDK_WINDOW_TEMP && window->x < 0 && window->y < 0)
    return FALSE;

which is not valid on Wayland I guess.

This causes Firefox bug https://bugzilla.mozilla.org/show_bug.cgi?id=1717451

Package gtk3-3.24.29-1.7.fc34.x86_64