make deprecated elements have low suggestion relevance

pkg/analysis_server/lib/src/services/completion/suggestion_builder.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.suggestion.builder;
 
 import 'package:analysis_server/src/protocol_server.dart' as protocol;
 import 'package:analysis_server/src/protocol_server.dart' hide Element,
     ElementKind;
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
@@ skipping 265 matching lines @@
       if (elementLibrary != unitLibrary) {
         return;
       }
     }
     String completion = element.displayName;
     if (completion == null ||
         completion.length <= 0 ||
         !_completions.add(completion)) {
       return;
     }
+    bool isDeprecated = element.isDeprecated;
     CompletionSuggestion suggestion = new CompletionSuggestion(
         kind,
-        CompletionRelevance.DEFAULT,
+        isDeprecated ? CompletionRelevance.LOW : CompletionRelevance.DEFAULT,
         completion,
         completion.length,
         0,
-        element.isDeprecated,
+        isDeprecated,
         false);
     suggestion.element = protocol.newElement_fromEngine(element);
     if (suggestion.element != null) {
       if (element is FieldElement) {
         suggestion.element.kind = protocol.ElementKind.GETTER;
         suggestion.element.returnType =
             element.type != null ? element.type.displayName : 'dynamic';
       }
     }
     if (enclosingElement != null) {
       suggestion.declaringType = enclosingElement.displayName;
     }
     if (type != null) {
       String typeName = type.displayName;
       if (typeName != null && typeName.length > 0 && typeName != 'dynamic') {
         suggestion.returnType = typeName;
       }
     }
     request.suggestions.add(suggestion);
   }
 }