refactor(transformer/es2019): move all entry points to implementation of Traverse trait (#5065)

follow-up #4881

crates/oxc_transformer/src/es2019/mod.rs

@@ -4,7 +4,7 @@ mod options;
 pub use optional_catch_binding::OptionalCatchBinding;
 pub use options::ES2019Options;
 use oxc_ast::ast::*;
-use oxc_traverse::TraverseCtx;
+use oxc_traverse::{Traverse, TraverseCtx};
 use std::rc::Rc;
 
 use crate::context::Ctx;
@@ -22,14 +22,12 @@ impl<'a> ES2019<'a> {
     pub fn new(options: ES2019Options, ctx: Ctx<'a>) -> Self {
         Self { optional_catch_binding: OptionalCatchBinding::new(Rc::clone(&ctx)), ctx, options }
     }
+}
 
-    pub fn transform_catch_clause(
-        &mut self,
-        clause: &mut CatchClause<'a>,
-        ctx: &mut TraverseCtx<'a>,
-    ) {
+impl<'a> Traverse<'a> for ES2019<'a> {
+    fn enter_catch_clause(&mut self, clause: &mut CatchClause<'a>, ctx: &mut TraverseCtx<'a>) {
         if self.options.optional_catch_binding {
-            self.optional_catch_binding.transform_catch_clause(clause, ctx);
+            self.optional_catch_binding.enter_catch_clause(clause, ctx);
         }
     }
 }

crates/oxc_transformer/src/es2019/optional_catch_binding.rs

@@ -37,7 +37,7 @@ use std::cell::Cell;
 use oxc_ast::ast::*;
 use oxc_semantic::SymbolFlags;
 use oxc_span::SPAN;
-use oxc_traverse::TraverseCtx;
+use oxc_traverse::{Traverse, TraverseCtx};
 
 use crate::context::Ctx;
 
@@ -49,10 +49,12 @@ impl<'a> OptionalCatchBinding<'a> {
     pub fn new(ctx: Ctx<'a>) -> Self {
         Self { _ctx: ctx }
     }
+}
 
+impl<'a> Traverse<'a> for OptionalCatchBinding<'a> {
     /// If CatchClause has no param, add a parameter called `unused`.
     #[allow(clippy::unused_self)]
-    pub fn transform_catch_clause(&self, clause: &mut CatchClause<'a>, ctx: &mut TraverseCtx<'a>) {
+    fn enter_catch_clause(&mut self, clause: &mut CatchClause<'a>, ctx: &mut TraverseCtx<'a>) {
         if clause.param.is_some() {
             return;
         }

crates/oxc_transformer/src/lib.rs

@@ -333,7 +333,7 @@ impl<'a> Traverse<'a> for Transformer<'a> {
     }
 
     fn enter_catch_clause(&mut self, clause: &mut CatchClause<'a>, ctx: &mut TraverseCtx<'a>) {
-        self.x2_es2019.transform_catch_clause(clause, ctx);
+        self.x2_es2019.enter_catch_clause(clause, ctx);
     }
 
     fn enter_ts_export_assignment(