Deprecate the generated AST library and clean up imports

pkg/analysis_server/lib/src/computer/computer_overrides.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.overrides;
 
 import 'package:analysis_server/src/collections.dart';
 import 'package:analysis_server/src/protocol_server.dart' as proto;
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
-import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/dart/ast/ast.dart';
 
 /**
  * Return the elements that the given [element] overrides.
  */
 OverriddenElements findOverriddenElements(Element element) {
   if (element?.enclosingElement is ClassElement) {
     return new _OverriddenElementsFinder(element).find();
   }
   return new OverriddenElements(element, <Element>[], <Element>[]);
 }
@@ skipping 208 matching lines @@
     if (_kinds.contains(ElementKind.SETTER)) {
       member = classElement.lookUpSetter(_name + '=', _library);
       if (member != null) {
         return member;
       }
     }
     // not found
     return null;
   }
 }