include inherited members in invocation suggestions

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/services/completion/completion_suggestion.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:analyzer/src/generated/element.dart';
 
 /**
  * This class visits elements in a class and provides suggestions based upon
  * the visible members in that class. Clients should call
  * [ClassElementSuggestionBuilder.suggestionsFor].
  */
 class ClassElementSuggestionBuilder extends GeneralizingElementVisitor {
   final DartCompletionRequest request;
+  final Set<String> _completions = new Set<String>();
 
   ClassElementSuggestionBuilder(this.request);
 
   @override
   visitClassElement(ClassElement element) {
     element.visitChildren(this);
+    element.allSupertypes.forEach((InterfaceType type) {
+      type.element.visitChildren(this);
+    });
   }
 
   @override
   visitElement(Element element) {
     // ignored
   }
 
   @override
   visitFieldElement(FieldElement element) {
     _addSuggestion(element, CompletionSuggestionKind.FIELD);
@@ skipping 20 matching lines @@
     if (element.isPrivate) {
       LibraryElement elementLibrary =
           element.getAncestor((parent) => parent is LibraryElement);
       LibraryElement unitLibrary =
           request.unit.element.getAncestor((parent) => parent is LibraryElement);
       if (elementLibrary != unitLibrary) {
         return;
       }
     }
     String completion = element.displayName;
-    if (completion == null || completion.length <= 0) {
+    if (completion == null ||
+        completion.length <= 0 ||
+        !_completions.add(completion)) {
       return;
     }
     request.suggestions.add(
         new CompletionSuggestion(
             kind,
             CompletionRelevance.DEFAULT,
             completion,
             completion.length,
             0,
             element.isDeprecated,
@@ skipping 66 matching lines @@
   /**
    * Add suggestions for the visible members in the given library
    */
   static void suggestionsFor(DartCompletionRequest request,
       LibraryElement library) {
     if (library != null) {
       library.visitChildren(new LibraryElementSuggestionBuilder(request));
     }
   }
 }