Add completion tests for the new analysis driver.

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

Index: pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
diff --git a/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
index 3968e24af06492e54bbc750facd694b837360614..a4d7b73ec50619a71de1c2dee6f49f458b469e12 100644
--- a/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
@@ -19,6 +19,7 @@ import 'completion_contributor_util.dart';
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LabelContributorTest);
+    defineReflectiveTests(LabelContributorTest_Driver);
   });
 }
 
@@ -324,3 +325,9 @@ void main() {
     assertSuggestLabel('foo');
   }
 }
+
+@reflectiveTest
+class LabelContributorTest_Driver extends LabelContributorTest {
+  @override
+  bool get enableNewAnalysisDriver => true;
+}