Test to ensure xdg_surface is not assigned non extending role

[i509VCB]

Per the documentation in xdg_wm_base.get_xdg_surface:

While xdg_surface itself is not a role, the corresponding surface may only be assigned a role extending xdg_surface, such as xdg_toplevel or xdg_popup

Talked with Simon about this on #wayland and he agrees that should exhibit a protocol error.