a11y: Remove unnecessary vfunc impl
a11y: Remove unnecessary vfunc impl

Layer is WIDGET by default, so there is no need to provide an overriding impl
returning the same.

flaxandteal/gasket-vte,saitoha/vte-sixel,flaxandteal/gasket-vte,saitoha/vte-sixel,rvu95/vte,jessevdk/vte,jessevdk/vte,thestinger/vte-ng,rvu95/vte,jessevdk/vte,rvu95/vte,flaxandteal/gasket-vte,thestinger/vte-ng,flaxandteal/gasket-vte,thestinger/vte-ng,jessevdk/vte,saitoha/vte-sixel,rvu95/vte