Assure dominance in lower_calls_with_compounds().

It currently uses dominance checks, though the use looks questionable.
backend/lower_call4.c is the only test case which triggers this check.
The check was added in bd1b1f0e.
Though later in 5f4cf6e0 another check was added, which would also handle this case for different reasons (target is not on the frame).
So at least the test case needs to be updated validate the dominance check.
Maybe the dominance check should be replaced by a dependence check.

ir/lower/lower_calls.c

@@ -944,7 +944,7 @@ static void transform_irg(lowering_env_t const *const env, ir_graph *const irg)
 	if (n_param_com > 0 && !(env->flags & LF_DONT_LOWER_ARGUMENTS))
 		remove_compound_param_entities(irg);
 
-	assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_ENTITY_USAGE);
+	assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE | IR_GRAPH_PROPERTY_CONSISTENT_ENTITY_USAGE);
 	fix_calls(&walk_env);
 	ir_free_resources(irg, IR_RESOURCE_IRN_LINK);