Fix regression with CSS fallback renderer.
Fix regression with CSS fallback renderer.

Regression caused rendering issue for cubemaps (but not multires) when CSS
fallback render was used. The regression was introduced as an optimization in
5eab5366f6987a4abdf648cbf5f7a243f14faf28.

mpetroff/pannellum,mpetroff/pannellum,mpetroff/pannellum,mpetroff/pannellum