Stop using LibraryElement.visibleLibraries getter.

test/codegen/recorder_test.dart

Index: test/codegen/recorder_test.dart
diff --git a/test/codegen/recorder_test.dart b/test/codegen/recorder_test.dart
index b2d8019558993588a84bb4826e3291d42768607a..912ca09e2b0b6992650e4719bc9b613cb7f1c548 100644
--- a/test/codegen/recorder_test.dart
+++ b/test/codegen/recorder_test.dart
@@ -89,8 +89,7 @@ main() {
       recorder.lookupParent(lib.getType('F2'));
       recorder.lookupParent(lib.getType('G'));
       recorder.lookupParent(lib.getType('H'));
-      var coreLib =
-          lib.visibleLibraries.firstWhere((l) => l.displayName == 'dart.core');
+      var coreLib = lib.context.typeProvider.objectType.element.library;
       recorder.lookupParent(coreLib.getType('int'));
       recorder.lookupParent(coreLib.getType('num'));