Move byte_store.dart and file_byte_store.dart to their own subdirectory.

pkg/analysis_server/test/services/search/search_engine_test.dart

 // Copyright (c) 2016, 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 'dart:async';
 
 import 'package:analysis_server/src/services/search/search_engine.dart';
 import 'package:analysis_server/src/services/search/search_engine_internal.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:front_end/src/base/performace_logger.dart';
-import 'package:front_end/src/incremental/byte_store.dart';
+import 'package:front_end/src/byte_store/byte_store.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../../mock_sdk.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SearchEngineImpl2Test);
   });
 }
@@ skipping 384 matching lines @@
       contentOverlay,
       null,
       new SourceFactory(
           [new DartUriResolver(sdk), new ResourceUriResolver(provider)],
           null,
           provider),
       new AnalysisOptionsImpl()..strongMode = true);
 
   String _p(String path) => provider.convertPath(path);
 }