Start actually adding incrementality into incremental kernel generator.

pkg/front_end/lib/compiler_options.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.
 
 library front_end.compiler_options;
 
 import 'dart:async';
+
+import 'package:front_end/src/base/performace_logger.dart';
+import 'package:front_end/src/incremental/byte_store.dart';
+
 import 'compilation_error.dart';
 import 'file_system.dart';
 import 'physical_file_system.dart';
 import 'src/simple_error.dart';
 
 /// Default error handler used by [CompilerOptions.onError].
 void defaultErrorHandler(CompilationError error) => throw error;
 
 /// Callback used to report errors encountered during compilation.
 typedef void ErrorHandler(CompilationError error);
@@ skipping 78 matching lines @@
   Map<String, String> declaredVariables;
 
   /// The [FileSystem] which should be used by the front end to access files.
   ///
   /// All file system access performed by the front end goes through this
   /// mechanism, with one exception: if no value is specified for
   /// [packagesFileUri], the packages file is located using the actual physical
   /// file system.  TODO(paulberry): fix this.
   FileSystem fileSystem = PhysicalFileSystem.instance;
 
+  /// The byte storage to get and put serialized data.
+  ByteStore byteStore = new NullByteStore();
+
+  /// The logger to report compilation progress.
+  PerformanceLog logger = new PerformanceLog(new StringBuffer());
+
   /// Whether to generate code for the SDK when compiling a whole-program.
   bool compileSdk = false;
 
   /// Whether a modular build compiles only the files listed explicitly or if it
   /// compiles dependencies as well.
   ///
   /// This option is intended only for modular APIs like `kernelForBuildUnit`.
   /// These APIs by default ensure that builds are hermetic, where all files
   /// that will be compiled are listed explicitly and all other dependencies
   /// are covered by summary files.
@@ skipping 38 matching lines @@
     return _report("SDK root directory not found: ${options.sdkRoot}");
   }
 
   var summary = options.sdkSummary;
   if (summary != null && !await fs.entityForUri(summary).exists()) {
     return _report("SDK summary not found: ${options.sdkSummary}");
   }
 
   return true;
 }