Remove the checker and corresponding dead code

test/all_tests.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.
 
 /// Meta-test that runs all tests we have written.
 library dev_compiler.test.all_tests;
 
 import 'package:test/test.dart';
 
-import 'checker/self_host_test.dart' as self_host;
 import 'closure/closure_annotation_test.dart' as closure_annotation_test;
 import 'closure/closure_type_test.dart' as closure_type_test;
 import 'codegen_test.dart' as codegen_test;
 import 'end_to_end_test.dart' as e2e;
 import 'report_test.dart' as report_test;
 import 'dependency_graph_test.dart' as dependency_graph_test;
 
 void main() {
   group('end-to-end', e2e.main);
   group('report', report_test.main);
   group('dependency_graph', dependency_graph_test.main);
   group('codegen', () => codegen_test.main([]));
-  group('self_host', self_host.main);
   group('closure', () {
     closure_annotation_test.main();
     closure_type_test.main();
   });
 }