tests: Use weston_surface_to_global_float
tests: Use weston_surface_to_global_float

Forgot to update use of weston_surface_to_global() here.

jonnylamb/weston,krezovic/weston,udoprog/weston,xorgy/weston,eyolfson/weston,kwm81/weston,xorgy/weston,mchalupa/weston,Tarnyko/weston-xdg_surface_present,udoprog/weston,krezovic/weston,Tarnyko/weston-xdg_surface_present,jonnylamb/weston,Fantu/compositor-spice,Fantu/compositor-spice,giucam/weston,Gnurou/weston,Gnurou/weston,mchalupa/weston,eyolfson/weston,sir-murray/weston,kwm81/weston,Fantu/compositor-spice,giucam/weston,sir-murray/weston