dart2js: Capture typedef arguments once

pkg/js_ast/lib/src/nodes.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_ast;
 
 abstract class NodeVisitor<T> {
   T visitProgram(Program node);
 
   T visitBlock(Block node);
@@ skipping 215 matching lines @@
     return clone;
   }
 
   VariableUse asVariableUse() => null;
 
   bool get isCommaOperator => false;
 
   Statement toStatement() {
     throw new UnsupportedError('toStatement');
   }
+
+  String debugPrint() => DebugPrint(this);
 }
 
 class Program extends Node {
   final List<Statement> body;
   Program(this.body);
 
   accept(NodeVisitor visitor) => visitor.visitProgram(this);
   void visitChildren(NodeVisitor visitor) {
     for (Statement statement in body) statement.accept(visitor);
   }
@@ skipping 1046 matching lines @@
 class Comment extends Statement {
   final String comment;
 
   Comment(this.comment);
 
   accept(NodeVisitor visitor) => visitor.visitComment(this);
   Comment _clone() => new Comment(comment);
 
   void visitChildren(NodeVisitor visitor) {}
 }