Deprecate the generated AST library and clean up imports

pkg/analysis_server/lib/src/computer/computer_outline.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.
 
 library computer.outline;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/collections.dart';
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart' as engine;
 import 'package:analyzer/dart/element/type.dart' as engine;
-import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 /**
  * A computer for [CompilationUnit] outline.
  */
 class DartUnitOutlineComputer {
   final String file;
   final CompilationUnit unit;
   final LineInfo lineInfo;
 
@@ skipping 378 matching lines @@
 }
 
 /**
  * A range of characters.
  */
 class _SourceRegion {
   final int length;
   final int offset;
   _SourceRegion(this.offset, this.length);
 }