Change analysis server protocol to omit empty lists when optional.

pkg/analysis_server/test/integration/server/set_subscriptions_test.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 test.integration.server.set.subscriptions;
 
 import 'dart:async';
 
 import 'package:analysis_testing/reflective_tests.dart';
 import 'package:unittest/unittest.dart';
 
 import '../integration_tests.dart';
 
 @ReflectiveTestCase()
 class Test extends AbstractAnalysisServerIntegrationTest {
   test_setSubscriptions() {
     bool statusReceived = false;
     Completer analysisBegun = new Completer();
     onServerStatus.listen((_) {
       statusReceived = true;
     });
     onAnalysisErrors.listen((_) {
       if (!analysisBegun.isCompleted) {
         analysisBegun.complete();
       }
     });
-    return sendServerSetSubscriptions([]).then((_) {
+    return sendServerSetSubscriptions().then((_) {
       String pathname = sourcePath('test.dart');
       writeFile(pathname, '''
 main() {
   var x;
 }''');
       standardAnalysisSetup(subscribeStatus: false);
       // Analysis should begin, but no server.status notification should be
       // received.
       return analysisBegun.future.then((_) {
         expect(statusReceived, isFalse);
-        return sendServerSetSubscriptions(['STATUS']).then((_) {
+        return sendServerSetSubscriptions(subscriptions: ['STATUS']).then((_) {
           // Tickle test.dart just in case analysis has already completed.
           writeFile(pathname, '''
 main() {
   var y;
 }''');
           // Analysis should eventually complete, and we should be notified
           // about it.
           return analysisFinished;
         });
       });
     });
   }
 }
 
 main() {
   runReflectiveTests(Test);
 }