Use ASTVisitor as in new AST.

compiler/java/com/google/dart/compiler/ast/DartFieldDefinition.java

 // Copyright (c) 2011, 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.
 
 package com.google.dart.compiler.ast;
 
 import java.util.List;
 
 /**
  * Represents a Dart field definition.
@@ skipping 14 matching lines @@
 
   public void setTypeNode(DartTypeNode typeNode) {
     this.typeNode = becomeParentOf(typeNode);
   }
 
   public List<DartField> getFields() {
     return fields;
   }
 
   @Override
-  public void traverse(DartVisitor v, DartContext ctx) {
-    if (v.visit(this, ctx)) {
-      if (getTypeNode() != null) {
-        setTypeNode(v.accept(getTypeNode()));
-      }
-      v.acceptWithInsertRemove(this, getFields());
-    }
-    v.endVisit(this, ctx);
-  }
-
-  @Override
-  public void visitChildren(DartPlainVisitor<?> visitor) {
+  public void visitChildren(ASTVisitor<?> visitor) {
     if (getTypeNode() != null) {
       getTypeNode().accept(visitor);
     }
     visitor.visit(getFields());
   }
 
   @Override
-  public <R> R accept(DartPlainVisitor<R> visitor) {
+  public <R> R accept(ASTVisitor<R> visitor) {
     return visitor.visitFieldDefinition(this);
   }
 }