convert ImportedReferenceContributor to new API

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

Index: pkg/analysis_server/test/services/completion/test_all.dart
diff --git a/pkg/analysis_server/test/services/completion/test_all.dart b/pkg/analysis_server/test/services/completion/test_all.dart
index 92e8bd4c911d0cbb0ea29c6149270f3052512f5a..a47c7c81b2f1949634a82388032490a8fcb94e45 100644
--- a/pkg/analysis_server/test/services/completion/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/test_all.dart
@@ -11,7 +11,6 @@ import 'completion_computer_test.dart' as completion_computer_test;
 import 'completion_manager_test.dart' as completion_manager_test;
 import 'completion_target_test.dart' as completion_target_test;
 import 'dart/test_all.dart' as dart_contributor_tests;
-import 'imported_reference_contributor_test.dart' as imported_test;
 import 'optype_test.dart' as optype_test;
 
 /// Utility for manually running all tests.
@@ -22,7 +21,6 @@ main() {
     completion_manager_test.main();
     completion_target_test.main();
     dart_contributor_tests.main();
-    imported_test.main();
     optype_test.main();
   });
 }