Clean up imports in analysis_server and analyzer_cli (and one missed in analyzer)

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:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/ast.dart';
-import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 
 /**
  * Determine the number of arguments.
  */
 int _argCount(DartCompletionRequest request) {
   AstNode node = request.target.containingNode;
   if (node is ArgumentList) {
     return node.arguments.length;
   }
@@ skipping 229 matching lines @@
       _addArgListSuggestion(requiredParam);
       return;
     }
     if (_isEditingNamedArgLabel(request) || _isAppendingToArgList(request)) {
       if (requiredCount == 0 || requiredCount < _argCount(request)) {
         _addDefaultParamSuggestions(parameters);
       }
     }
   }
 }