Implement IncrementalKernelGeneratorImpl using KernelDriver.

pkg/front_end/test/incremental_kernel_generator_test.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 'dart:async';
 
 import 'package:front_end/compiler_options.dart';
 import 'package:front_end/incremental_kernel_generator.dart';
 import 'package:front_end/memory_file_system.dart';
 import 'package:front_end/src/fasta/kernel/utils.dart';
@@ skipping 826 matching lines @@
     fileSystem.entityForUri(uri).writeAsStringSync(text);
     return uri;
   }
 
   /// Write the given file contents to the virtual filesystem.
   void writeFiles(Map<String, String> contents) {
     contents.forEach(writeFile);
   }
 
   void _assertCompiledUris(Iterable<Uri> expected) {
-    var compiledCycles = incrementalKernelGenerator.test.compiledCycles;
+    var compiledCycles =
+        incrementalKernelGenerator.test.driver.test.compiledCycles;
     Set<Uri> compiledUris = compiledCycles
         .map((cycle) => cycle.libraries.map((file) => file.uri))
         .expand((uris) => uris)
         .toSet();
     expect(compiledUris, unorderedEquals(expected));
   }
 
   void _assertLibraryUris(Program program,
       {List<Uri> includes: const [], List<Uri> excludes: const []}) {
     List<Uri> libraryUris =
@@ skipping 13 matching lines @@
     throw fail('No library found with URI "$uri"');
   }
 
   String _getLibraryText(Library library) {
     StringBuffer buffer = new StringBuffer();
     new Printer(buffer, syntheticNames: new NameSystem())
         .writeLibraryFile(library);
     return buffer.toString();
   }
 }