Move flat_buffer and api_signature into front_end.

pkg/front_end/test/src/base/test_all.dart

+// Copyright (c) 2017, 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 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'api_signature_test.dart' as api_signature;
+import 'file_repository_test.dart' as file_repository;
+import 'flat_buffers_test.dart' as flat_buffers;
+import 'libraries_reader_test.dart' as libraries_reader;
+import 'processed_options_test.dart' as processed_options;
+import 'uri_resolver_test.dart' as uri_resolver;
+
+/// Utility for manually running all tests.
+main() {
+  defineReflectiveSuite(() {
+    api_signature.main();
+    file_repository.main();
+    flat_buffers.main();
+    libraries_reader.main();
+    processed_options.main();
+    uri_resolver.main();
+  }, name: 'incremental');
+}