[MC-89978] Small mobs drown in boats

The following mobs drown when riding a boat on water: (They probably also suffocate when riding a boat on land)

Small Slimes, Small Magma Cubes, Cave Spiders, Silverfish, Endermites, Bats, Shulkers, Baby Pigs, Baby Chickens, Baby Wolves, Baby Ocelots, (Baby) Rabbits

To reproduce this bug for yourself, use the following command:

/summon Boat ~ ~ ~ {Passengers:[{id:"ENTITY"}]}

To modify the size of the entities, use the following NBT tags:

Pigs, Cows, Sheep, Chickens, Mooshrooms, Ocelots, Wolves, Rabbits, and Horses: Age:X (-9999 for baby, 0 for adult)

/summon Boat ~ ~ ~ {Passengers:[{id:"ENTITY",Age:X}]}

Zombies, Zombie Pigmen, Villagers: IsBaby:X (1 for baby, 0 for adult)

/summon Boat ~ ~ ~ {Passengers:[{id:"ENTITY",IsBaby:X}]}

Slimes and Magma Cubes: Size:X (0 for small, 1 for medium, 2 for large)

/summon Boat ~ ~ ~ {Passengers:[{id:"ENTITY",Size:X}]}