hasShadowLayer

true when an enabled earth.worldwind.layer.shadow.ShadowLayer is present in layers for this frame. Computed once at the start of earth.worldwind.WorldWind.renderFrame before any Layer.render runs, so receivers that touch every visible fragment (surface tiles, atmosphere ground) can pick the smaller-binary no-shadow shader variant up-front. Independent of shadowState, which is populated later by earth.worldwind.layer.shadow.ShadowLayer.doRender.