Skip SDK summaries in the presence of SDK extenders (#26448).

pkg/analyzer_cli/test/all.dart

 // Copyright (c) 2015, 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.
 
 import 'boot_loader_test.dart' as boot_loader;
 import 'build_mode_test.dart' as build_mode_test;
 import 'driver_test.dart' as driver;
 import 'embedder_test.dart' as embedder;
 import 'error_test.dart' as error;
 import 'options_test.dart' as options;
 import 'package_prefix_test.dart' as package_prefix;
 import 'perf_report_test.dart' as perf;
 import 'plugin_manager_test.dart' as plugin_manager;
 import 'reporter_test.dart' as reporter;
+import 'sdk_ext_test.dart' as sdk_ext;
 import 'super_mixin_test.dart' as super_mixin;
-//import 'sdk_ext_test.dart' as sdk_ext;
 //import 'strong_mode_test.dart' as strong_mode;
 
 main() {
   boot_loader.main();
   build_mode_test.main();
   driver.main();
   embedder.main();
+  sdk_ext.main();
   // TODO(pq): fix tests to run safely on the bots
   // https://github.com/dart-lang/sdk/issues/25001
-  //sdk_ext.main();
   //strong_mode.main();
   error.main();
   options.main();
   perf.main();
   plugin_manager.main();
   reporter.main();
   super_mixin.main();
   package_prefix.main();
 }