Grass blocks can sometimes generate in Mushroom Islands

Rarely, there is grass on the shore of a Mushroom Island. It is usually only 2 or 3 blocks, but it may be more.

Steps to Reproduce:

1. Create a new world with the seed: 1772835215
2. Go to -8355 71 -2170

Observed Results:
Grass blocks generate in the Mushroom Island.

Expected Results:
Grass blocks should not generate in Mushroom Islands.