Fix T58899: Eevee - Material Index missing from panel

Referenced by issue #58899, Blender 2.8 - Eevee - Material Index is missing from the materials menu

release/scripts/startup/bl_ui/properties_material.py

@@ -234,6 +234,7 @@ class EEVEE_MATERIAL_PT_settings(MaterialButtonsPanel, Panel):
         layout.prop(mat, "use_screen_refraction")
         layout.prop(mat, "refraction_depth")
         layout.prop(mat, "use_sss_translucency")
+        layout.prop(mat, "pass_index")
 
     def draw(self, context):
         self.draw_shared(self, context.material)