Prioritize required name param completions (flutter-intellij#1049).

pkg/analyzer_plugin/lib/utilities/completion/relevance.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.
 
 //
 // Constant values used for relevance values when creating completion
 // suggestions in Dart code.
 //
 
 const int DART_RELEVANCE_COMMON_USAGE = 1200;
 const int DART_RELEVANCE_DEFAULT = 1000;
 const int DART_RELEVANCE_HIGH = 2000;
 const int DART_RELEVANCE_INCREMENT = 100;
 const int DART_RELEVANCE_INHERITED_ACCESSOR = 1057;
 const int DART_RELEVANCE_INHERITED_FIELD = 1058;
 const int DART_RELEVANCE_INHERITED_METHOD = 1057;
 const int DART_RELEVANCE_KEYWORD = 1055;
 const int DART_RELEVANCE_LOCAL_ACCESSOR = 1057;
 const int DART_RELEVANCE_LOCAL_FIELD = 1058;
 const int DART_RELEVANCE_LOCAL_FUNCTION = 1056;
 const int DART_RELEVANCE_LOCAL_METHOD = 1057;
 const int DART_RELEVANCE_LOCAL_TOP_LEVEL_VARIABLE = 1056;
 const int DART_RELEVANCE_LOCAL_VARIABLE = 1059;
 const int DART_RELEVANCE_LOW = 500;
 const int DART_RELEVANCE_NAMED_PARAMETER = 1060;
+const int DART_RELEVANCE_NAMED_PARAMETER_REQUIRED = 1065;
 const int DART_RELEVANCE_PARAMETER = 1059;