few small analyzer AST visitor fixes

pkg/analyzer/lib/src/generated/ast.dart

 // Copyright (c) 2014, 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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.ast;
 
 import 'dart:collection';
@@ skipping 1599 matching lines @@
       new TypeParameterList(cloneToken(node.leftBracket),
           cloneNodeList(node.typeParameters), cloneToken(node.rightBracket));
 
   @override
   VariableDeclaration visitVariableDeclaration(VariableDeclaration node) =>
       new VariableDeclaration(cloneNode(node.name), cloneToken(node.equals),
           cloneNode(node.initializer));
 
   @override
   VariableDeclarationList visitVariableDeclarationList(
-      VariableDeclarationList node) => new VariableDeclarationList(null,
+      VariableDeclarationList node) => new VariableDeclarationList(
+      cloneNode(node.documentationComment),
       cloneNodeList(node.metadata), cloneToken(node.keyword),
       cloneNode(node.type), cloneNodeList(node.variables));
 
   @override
   VariableDeclarationStatement visitVariableDeclarationStatement(
       VariableDeclarationStatement node) => new VariableDeclarationStatement(
       cloneNode(node.variables), cloneToken(node.semicolon));
 
   @override
   WhileStatement visitWhileStatement(WhileStatement node) => new WhileStatement(
@@ skipping 18576 matching lines @@
   }
 
   @override
   accept(AstVisitor visitor) => visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _safelyVisitChild(_expression, visitor);
   }
 }