Add completion tests for the new analysis driver.

pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart

Index: pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
diff --git a/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
index 78a6f4e38088bf54f9466c928c8f8d5647108522..5d7c0856c0968a4258796e877ae29dffe980ba77 100644
--- a/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
@@ -15,6 +15,7 @@ import 'completion_contributor_util.dart';
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ArgListContributorTest);
+    defineReflectiveTests(ArgListContributorTest_Driver);
   });
 }
 
@@ -631,3 +632,9 @@ main() { f("16", radix: ^);}''');
     assertSuggestArgumentList(['arg', 'blat'], ['dynamic', 'int']);
   }
 }
+
+@reflectiveTest
+class ArgListContributorTest_Driver extends ArgListContributorTest {
+  @override
+  bool get enableNewAnalysisDriver => true;
+}