Implement subtype relation for kernel based elements.

tests/compiler/dart2js/kernel/closed_world_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.
 
 // Tests that the closed world computed from [WorldImpact]s derived from kernel
 // is equivalent to the original computed from resolution.
 library dart2js.kernel.closed_world_test;
 
 import 'package:async_helper/async_helper.dart';
-import 'package:compiler/src/closure.dart';
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/common_elements.dart';
 import 'package:compiler/src/common/backend_api.dart';
 import 'package:compiler/src/common/resolution.dart';
 import 'package:compiler/src/common/work.dart';
 import 'package:compiler/src/compiler.dart';
-import 'package:compiler/src/deferred_load.dart';
 import 'package:compiler/src/elements/resolution_types.dart';
 import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/elements/entities.dart';
-import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/enqueue.dart';
 import 'package:compiler/src/js_backend/backend.dart';
-import 'package:compiler/src/js_backend/backend_impact.dart';
 import 'package:compiler/src/js_backend/backend_usage.dart';
-import 'package:compiler/src/js_backend/custom_elements_analysis.dart';
-import 'package:compiler/src/js_backend/native_data.dart';
-import 'package:compiler/src/js_backend/impact_transformer.dart';
 import 'package:compiler/src/js_backend/interceptor_data.dart';
-import 'package:compiler/src/js_backend/lookup_map_analysis.dart';
-import 'package:compiler/src/js_backend/mirrors_analysis.dart';
-import 'package:compiler/src/js_backend/mirrors_data.dart';
-import 'package:compiler/src/js_backend/no_such_method_registry.dart';
 import 'package:compiler/src/js_backend/resolution_listener.dart';
 import 'package:compiler/src/js_backend/type_variable_handler.dart';
-import 'package:compiler/src/native/enqueue.dart';
-import 'package:compiler/src/kernel/world_builder.dart';
-import 'package:compiler/src/options.dart';
 import 'package:compiler/src/ssa/kernel_impact.dart';
 import 'package:compiler/src/serialization/equivalence.dart';
 import 'package:compiler/src/universe/world_builder.dart';
 import 'package:compiler/src/universe/world_impact.dart';
 import 'package:compiler/src/world.dart';
-import 'package:kernel/ast.dart' as ir;
 import 'impact_test.dart';
 import '../memory_compiler.dart';
 import '../serialization/helper.dart';
 import '../serialization/model_test_helper.dart';
 
 const SOURCE = const {
   'main.dart': '''
 abstract class A {
   // redirecting factory in abstract class to other class
   factory A.a() = D.a;
@@ skipping 62 matching lines @@
             backend, compiler.resolution, const OpenWorldStrategy()),
         new KernelWorkItemBuilder(compiler),
         'enqueuer from kernel');
     ClosedWorld closedWorld = computeClosedWorld(
         compiler.reporter, enqueuer, compiler.elementEnvironment);
     BackendUsage backendUsage = backendUsageBuilder.close();
     checkResolutionEnqueuers(
         backendUsage, backendUsage, compiler.enqueuer.resolution, enqueuer,
         typeEquivalence: (ResolutionDartType a, ResolutionDartType b) {
       return areTypesEquivalent(unalias(a), unalias(b));
-    }, elementFilter: (Element element) {
-      if (element is ConstructorElement && element.isRedirectingFactory) {
-        // Redirecting factory constructors are skipped in kernel.
-        return false;
-      }
-      if (element is ClassElement) {
-        for (ConstructorElement constructor in element.constructors) {
-          if (!constructor.isRedirectingFactory) {
-            return true;
-          }
-        }
-        // The class cannot itself be instantiated.
-        return false;
-      }
-      return true;
-    }, verbose: arguments.verbose);
+    }, elementFilter: elementFilter, verbose: arguments.verbose);
     checkClosedWorlds(
         compiler.resolutionWorldBuilder.closedWorldForTesting, closedWorld,
         verbose: arguments.verbose);
   });
 }
 
+bool elementFilter(Entity element) {
+  if (element is ConstructorElement && element.isRedirectingFactory) {
+    // Redirecting factory constructors are skipped in kernel.
+    return false;
+  }
+  if (element is ClassElement) {
+    for (ConstructorElement constructor in element.constructors) {
+      if (!constructor.isRedirectingFactory) {
+        return true;
+      }
+    }
+    // The class cannot itself be instantiated.
+    return false;
+  }
+  return true;
+}
+
 List createResolutionEnqueuerListener(Compiler compiler) {
   JavaScriptBackend backend = compiler.backend;
   BackendUsageBuilder backendUsageBuilder =
       new BackendUsageBuilderImpl(compiler.commonElements);
   ResolutionEnqueuerListener listener = new ResolutionEnqueuerListener(
       compiler.options,
       compiler.elementEnvironment,
       compiler.commonElements,
       backend.impacts,
       backend.nativeBasicData,
@@ skipping 42 matching lines @@
   final MemberElement element;
 
   KernelWorkItem(this._compiler, this._impactTransformer, this.element);
 
   @override
   WorldImpact run() {
     ResolutionImpact resolutionImpact = build(_compiler, element.resolvedAst);
     return _impactTransformer.transformResolutionImpact(resolutionImpact);
   }
 }