Sunlight Block

You know how there's that one creative-only Light block? The one that just acts like air, except it provides light level? Well, I thought of a block that would have a similar purpose.

The Sunlight block would basically work as follows: You place one in the world, and any block below it ignores what's above the Sunlight block for the purposes of sky light level.

Why do I think this is a worthwhile addition to the game? Simple: Floating Islands. If the Sunlight block gets implemented you could make a floating island without having to worry about super-big shadows covering the entire world below. Said block would also naturally let what's beneath it darken as night falls, unlike the Light block we have. It could also theoretically be good for optimization for super-sized worlds, considering one block doesn't necessarily have to update the light level of hundreds of blocks below it.