[analyzer] remove "auto-generated do not edit" comments

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';
 
 import 'element.dart';
 import 'engine.dart' show AnalysisEngine;
 import 'java_core.dart';
 import 'java_engine.dart';
 import 'parser.dart';
 import 'scanner.dart';
@@ skipping 20179 matching lines @@
   }
 
   @override
   accept(AstVisitor visitor) => visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _safelyVisitChild(_expression, visitor);
   }
 }