Deprecate the generated AST library and clean up imports

pkg/analysis_server/lib/src/services/completion/dart/label_contributor.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 services.completion.contributor.dart.label;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart' as protocol
     show Element, ElementKind;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/services/completion/dart/completion_manager.dart'
     show DartCompletionRequestImpl;
 import 'package:analysis_server/src/services/completion/dart/local_declaration_visitor.dart'
     show LocalDeclarationVisitor;
 import 'package:analysis_server/src/services/completion/dart/optype.dart';
+import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/src/dart/ast/token.dart';
-import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 import '../../../protocol_server.dart'
     show CompletionSuggestion, CompletionSuggestionKind, Location;
 
 const DYNAMIC = 'dynamic';
 
 final TypeName NO_RETURN_TYPE = new TypeName(
     new SimpleIdentifier(new StringToken(TokenType.IDENTIFIER, '', 0)), null);
 
@@ skipping 248 matching lines @@
             0,
             false,
             false);
         suggestions.add(suggestion);
         return suggestion;
       }
     }
     return null;
   }
 }