Add ElementCodegenWorldBuilder

pkg/compiler/lib/src/kernel/kernel_strategy.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.
 
 library dart2js.kernel.frontend_strategy;
 
 import '../closure.dart';
 import '../backend_strategy.dart';
 import '../common.dart';
 import '../common_elements.dart';
 import '../common/backend_api.dart';
+import '../common/codegen.dart' show CodegenWorkItem;
 import '../common/resolution.dart';
 import '../common/tasks.dart';
 import '../common/work.dart';
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../elements/types.dart';
 import '../environment.dart' as env;
 import '../enqueue.dart';
 import '../frontend_strategy.dart';
 import '../js_backend/backend.dart';
@@ skipping 227 matching lines @@
   @override
   Sorter get sorter =>
       throw new UnimplementedError('KernelBackendStrategy.sorter');
 
   @override
   void convertClosures(ClosedWorldRefiner closedWorldRefiner) {
     // TODO(johnniwinther,efortuna): Compute closure classes for kernel based
     // elements.
     throw new UnimplementedError('KernelBackendStrategy.createClosureClasses');
   }
+
+  @override
+  WorkItemBuilder createCodegenWorkItemBuilder(ClosedWorld closedWorld) {
+    return new KernelCodegenWorkItemBuilder();
+  }
+
+  @override
+  CodegenWorldBuilder createCodegenWorldBuilder(
+      NativeBasicData nativeBasicData,
+      ClosedWorld closedWorld,
+      SelectorConstraintsStrategy selectorConstraintsStrategy) {
+    return new KernelCodegenWorldBuilder(
+        null, nativeBasicData, closedWorld, selectorConstraintsStrategy);
+  }
 }
+
+class KernelCodegenWorkItemBuilder implements WorkItemBuilder {
+  @override
+  CodegenWorkItem createWorkItem(MemberEntity entity) {
+    throw new UnimplementedError('KernelCodegenWorkItemBuilder.createWorkItem');
+  }
+}