Remove the checker and corresponding dead code

test/checker/self_host_test.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.
-
-/// Tests that run the checker end-to-end using the file system.
-library dev_compiler.test.checker.self_host_test;
-
-import 'package:dev_compiler/devc.dart' show BatchCompiler;
-import 'package:dev_compiler/src/options.dart';
-import 'package:test/test.dart';
-import '../testing.dart' show testDirectory, realSdkContext;
-
-void main() {
-  test('checker can run on itself ', () {
-    new BatchCompiler(realSdkContext, new CompilerOptions())
-        .compileFromUriString('$testDirectory/all_tests.dart');
-  }, skip: 'test is very slow');
-}