Revert "COW: Edit Mesh: Do not copy the looptris pointer"

The looptri is repeated in the linked Meshes but the pointer
is only referenced in the evaluated ones.

This reverts commit 64982e213f.

source/blender/editors/object/object_hook.c

@@ -351,7 +351,6 @@ static bool object_hook_index_array(Main *bmain,
 
       em = me->edit_mesh;
 
-      BLI_assert(DEG_is_original_object(obedit));
       EDBM_mesh_normals_update(em);
       BKE_editmesh_looptri_calc(em);