Remove unused collect_parameter_slots

This function was no longer being called and was removed as part of a
refactoring.

src/ast/compiler/optimizer/engine.rs

@@ -581,7 +581,6 @@ impl Optimizer {
                 }
 
                 let params_opt = self.visit_node(params.clone(), &mut next_inner_subs, path);
-                inliner.collect_parameter_slots(&params_opt, &mut next_inner_subs);
 
                 let body_opt = self.visit_node(body.clone(), &mut next_inner_subs, path);
                 let reindexed_body = if new_upvalues.len() != upvalues.len() {