Unify the server and plugin versions of the generators

pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart

 // Copyright (c) 2017, 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.src.completion.statement;
 
 import 'dart:async';
 
-import 'package:analysis_server/plugin/protocol/protocol.dart';
+import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/source_buffer.dart';
 import 'package:analysis_server/src/services/correction/source_range.dart';
 import 'package:analysis_server/src/services/correction/util.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/error.dart' as engine;
 import 'package:analyzer/src/dart/ast/utilities.dart';
@@ skipping 851 matching lines @@
   final Token keyword;
   final Token leftParenthesis, rightParenthesis;
   final Expression condition;
   final Statement block;
 
   _KeywordConditionBlockStructure(this.keyword, this.leftParenthesis,
       this.condition, this.rightParenthesis, this.block);
 
   int get offset => keyword.offset;
 }