Using an end gateway teleports the player half a block too high

The bug

When you use an end gateway, you get teleported half a block too high. This also relates to MC-3328 where the player was 0.5 blocks too high when dismounting. If you get teleported to a bottom slab, you will be at the correct hight.

How to reproduce:
1. Get an end gateway somewhere
2. Make sure to be in flying mode
3. Press F3
4. Use the end gateway
What happened: You will see that you are half a block too high.
What I expected: You will be on the ground.