Use NodeList where possible.

compiler/java/com/google/dart/compiler/ast/DartFunction.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 function.
  */
 public class DartFunction extends DartNode {
 
-  private final List<DartParameter> params;
+  private final NodeList<DartParameter> parameters = NodeList.create(this);
   private DartBlock body;
   private DartTypeNode returnTypeNode;
 
-  public DartFunction(List<DartParameter> arguments, DartBlock body, DartTypeNode returnTypeNode) {
-    this.params = becomeParentOf(arguments);
+  public DartFunction(List<DartParameter> parameters, DartBlock body, DartTypeNode returnTypeNode) {
+    this.parameters.addAll(parameters);
     this.body = becomeParentOf(body);
     this.returnTypeNode = becomeParentOf(returnTypeNode);
   }
 
-  public void addParam(DartParameter param) {
-    params.add(param);
-  }
-
   public DartBlock getBody() {
     return body;
   }
 
-  public List<DartParameter> getParams() {
-    return params;
+  public List<DartParameter> getParameters() {
+    return parameters;
   }
 
   public DartTypeNode getReturnTypeNode() {
     return returnTypeNode;
   }
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    visitor.visit(params);
+    parameters.accept(visitor);
     if (body != null) {
       body.accept(visitor);
     }
     if (returnTypeNode != null) {
       returnTypeNode.accept(visitor);
     }
   }
 
   @Override
   public <R> R accept(ASTVisitor<R> visitor) {
     return visitor.visitFunction(this);
   }
 }