Mangrove roots can replace bedrock (or any block in general)

Mangrove tree (roots to be specific) can replace bedrock (or any block) really when grown by bonemealing propagule.

Steps to reproduce:

1. Place a propagule under the block you want to replace.
2. Bonemeal the propagule
3. After a successful growth, there's a chance that block will be replaced with root or air.