Players in Spectator mode get slowed down when flying downward in scaffolding

Players in Spectator mode get slowed down when flying downward in scaffolding, relates to MCPE-153877.

Steps to Reproduce:

1. Place some scaffolding.
2. Enter Spectator mode (/gamemode spectator).
3. Fly downward in scaffolding.
4. Observe that you get slowed down.

Observed Results:
You will get slowed down by flying downward in scaffolding in Spectator mode. 

Expected Results:
You shouldn't get slowed down by flying downward in scaffolding in Spectator mode.

Screenshots/Videos attached: ScaffoldingSlows.mp4