Sculk cannot spread into stone slabs or stairs.

Sculk cannot spread into stone slabs and stairs, despite being able to spread to a full stone block.

Steps to Reproduce:  

1. Place a sculk catalyst
2. Put stone slabs and/or stairs near it
3. (Optional) Put a full stone block near it
4. Spawn in a zombie and slay it

Observed Results:

The sculk fails to spread to the stone slabs and/or stairs, but successfully spreads to the stone.

Expected Results:

The sculk would spread to the stone cube, stairs, and slab.

Notes:

This probably would be resolved as Won't Fix, but I thought I would make the report anyways just to be sure.