Deprecate the generated AST library and clean up imports

pkg/analysis_server/lib/src/status/ast_writer.dart

 // Copyright (c) 2015, 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.
 
 library analysis_server.src.status.ast_writer;
 
 import 'dart:collection';
 
 import 'package:analysis_server/src/status/tree_writer.dart';
-import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
 
 /**
  * A visitor that will produce an HTML representation of an AST structure.
  */
 class AstWriter extends UnifyingAstVisitor with TreeWriter {
   /**
    * Initialize a newly created element writer to write the HTML representation
    * of visited nodes on the given [buffer].
    */
   AstWriter(StringBuffer buffer) {
@@ skipping 147 matching lines @@
     buffer.write(node.offset);
     buffer.write('..');
     buffer.write(node.offset + node.length - 1);
     buffer.write(']</span>');
     if (node.isSynthetic) {
       buffer.write(' (synthetic)');
     }
     buffer.write('<br>');
   }
 }