only send final completion notification

pkg/analysis_server/lib/src/services/completion/dart_completion_manager.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.dart;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 165 matching lines @@
       }
 
       List<DartCompletionContributor> todo = new List.from(contributors);
       todo.removeWhere((DartCompletionContributor c) {
         return performance.logElapseTime('computeFast ${c.runtimeType}', () {
           return c.computeFast(request);
         });
       });
       contributionSorter.sort(
           new OldRequestWrapper(request), request.suggestions);
-      sendResults(request, todo.isEmpty);
+
+      if (todo.isEmpty) {
+        sendResults(request, todo.isEmpty);
+      }
       return todo;
     });
   }
 
   /**
    * If there is remaining work to be done, then wait for the unit to be
    * resolved and request that each remaining contributor finish their work.
    * Return a [Future] that completes when the last notification has been sent.
    */
   Future computeFull(DartCompletionRequest request,
@@ skipping 290 matching lines @@
 
   @override
   CompletionTarget get target => request.target;
 
   @override
   CompilationUnit get unit => request.unit;
 
   @override
   String toString() => 'wrapped $request';
 }