Map color for mangrove slab is incorrect

The bug

The map color for mangrove slabs is incorrect. Unlike mangrove planks, which appear red on a map, mangrove slabs appear brown on a map. This behavior is inconsistent with the behavior of other types of wood, which use the same color on maps for both their slabs and their planks.

How to reproduce

1. Obtain and fill a map
2. Place oak slabs and planks
   The slabs and planks appear brown on the map
3. Place mangrove slabs and planks
   The planks appear red, but the slabs appear brown on the map

Expected behavior

The mangrove slab color would be red, like the map color of mangrove planks.

Actual behavior

The mangrove slab color is brown, like the map color of oak planks and slabs.