Powder Snow slowness effect doesn't work when block below is not a full block

Powder Snow block's slowness effect does not if the very bottom of the player isn't touching the block. This results in being able to walk full speed in powder snow if the block under it is smaller than a full block (i.e. Dirt Path blocks, slabs, blocks like Enchanting tables, End Portal frames, Stonecutters, Campfires, Chains and End rods, etc.)