Player's descending speed in water is unaffected by an Elytra being active

Steps to Reproduce:

1. Find a large body of water

2. Position yourself at the top of it and then let yourself descend (to avoid momentum affecting the speed)

3. Leave the water

4. Give yourself an Elytra

5. Use the Elytra to glide into the water, keeping the camera as straight forward as possible

Observed Results:  

Player descends at the same speed in water regardless of an active Elytra

Expected Results:  

Player descends slower in liquids with an active Elytra