only send final completion notification

pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart

Index: pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart b/pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart
index 17806fe0c81cd816c9728fb220c63113e470ee74..2f19c646104a20328d9e214cb684a3e64a1f59aa 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart
@@ -183,7 +183,10 @@ class DartCompletionManager extends CompletionManager {
       });
       contributionSorter.sort(
           new OldRequestWrapper(request), request.suggestions);
-      sendResults(request, todo.isEmpty);
+
+      if (todo.isEmpty) {
+        sendResults(request, todo.isEmpty);
+      }
       return todo;
     });
   }