Object Layer property now has tag "not animatable".

Even with new depsgraph that'll be a big problem to support.
For as long layers define relationships or define evaluation
this should remain a static state.

Instead, animate outliner "visibility".

source/blender/makesrna/intern/rna_object.c

@@ -2082,6 +2082,7 @@ static void rna_def_object(BlenderRNA *brna)
 	RNA_def_property_boolean_funcs(prop, NULL, "rna_Object_layer_set");
 	RNA_def_property_flag(prop, PROP_LIB_EXCEPTION);
 	RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, "rna_Object_layer_update");
+	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
 
 	prop = RNA_def_property(srna, "layers_local_view", PROP_BOOLEAN, PROP_LAYER_MEMBER);
 	RNA_def_property_boolean_sdna(prop, NULL, "lay", 0x01000000);