Remove more libraries directives from server

pkg/analysis_server/lib/src/services/completion/dart/arglist_contributor.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 services.completion.contributor.dart.arglist;
-
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart'
     hide Element, ElementKind;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/services/completion/dart/utilities.dart';
 import 'package:analysis_server/src/services/correction/flutter_util.dart';
 import 'package:analysis_server/src/utilities/documentation.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 311 matching lines @@
    */
   static void _setDocumentation(
       CompletionSuggestion suggestion, String comment) {
     if (comment != null) {
       String doc = removeDartDocDelimiters(comment);
       suggestion.docComplete = doc;
       suggestion.docSummary = getDartDocSummary(doc);
     }
   }
 }