Moving through cobwebs in Spectator mode and changing game mode to survival/adventure after moving away slows down the player for a brief period

Related to MC-279016, MC-279021, MC-279030, MC-279031 and MC-279032.

Moving through cobwebs while in spectator mode, and then changing the gamemode to survival or adventure slows the player for a brief period.

Steps to Reproduce:

1. While in spectator mode, fly through a cobweb.

2. Change the player's game mode to survival or adventure.

Observed Results:

The player slows down for a brief period despite leaving the block while in spectator mode.

Expected Results:

The player does not slow down.