Create SsaBuilderTask stub for KernelBackendStrategy

pkg/compiler/lib/src/kernel/kernel_strategy.dart

Index: pkg/compiler/lib/src/kernel/kernel_strategy.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_strategy.dart b/pkg/compiler/lib/src/kernel/kernel_strategy.dart
index 842b3e331d653fece8ebd4932ea39353f8087775..457f89639024eade683d564dc1719f2ffdd22de6 100644
--- a/pkg/compiler/lib/src/kernel/kernel_strategy.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_strategy.dart
@@ -13,12 +13,14 @@ import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/resolution.dart';
 import '../common/tasks.dart';
 import '../common/work.dart';
+import '../compiler.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 '../io/source_information.dart';
 import '../js_backend/backend.dart';
 import '../js_backend/backend_usage.dart';
 import '../js_backend/custom_elements_analysis.dart';
@@ -32,6 +34,8 @@ import '../js_emitter/sorter.dart';
 import '../library_loader.dart';
 import '../native/resolver.dart';
 import '../serialization/task.dart';
+import '../ssa/builder_kernel.dart';
+import '../ssa/ssa.dart';
 import '../patch_parser.dart';
 import '../resolved_uri_translator.dart';
 import '../universe/world_builder.dart';
@@ -243,6 +247,10 @@ class MirrorsResolutionAnalysisImpl implements MirrorsResolutionAnalysis {
 // TODO(johnniwinther): Replace this with a strategy based on the J-element
 // model.
 class KernelBackendStrategy implements BackendStrategy {
+  final Compiler _compiler;
+
+  KernelBackendStrategy(this._compiler);
+
   @override
   ClosedWorldRefiner createClosedWorldRefiner(KernelClosedWorld closedWorld) {
     return closedWorld;
@@ -260,7 +268,7 @@ class KernelBackendStrategy implements BackendStrategy {
 
   @override
   WorkItemBuilder createCodegenWorkItemBuilder(ClosedWorld closedWorld) {
-    return new KernelCodegenWorkItemBuilder();
+    return new KernelCodegenWorkItemBuilder(_compiler.backend, closedWorld);
   }
 
   @override
@@ -268,8 +276,14 @@ class KernelBackendStrategy implements BackendStrategy {
       NativeBasicData nativeBasicData,
       ClosedWorld closedWorld,
       SelectorConstraintsStrategy selectorConstraintsStrategy) {
-    return new KernelCodegenWorldBuilder(
-        null, nativeBasicData, closedWorld, selectorConstraintsStrategy);
+    return new KernelCodegenWorldBuilder(_compiler.elementEnvironment,
+        nativeBasicData, closedWorld, selectorConstraintsStrategy);
+  }
+
+  @override
+  SsaBuilderTask createSsaBuilderTask(JavaScriptBackend backend,
+      SourceInformationStrategy sourceInformationStrategy) {
+    return new KernelSsaBuilderTask(backend.compiler.measurer);
   }
 }
 
@@ -287,21 +301,28 @@ class MirrorsCodegenAnalysisImpl implements MirrorsCodegenAnalysis {
 }
 
 class KernelCodegenWorkItemBuilder implements WorkItemBuilder {
+  final JavaScriptBackend _backend;
+  final ClosedWorld _closedWorld;
+
+  KernelCodegenWorkItemBuilder(this._backend, this._closedWorld);
+
   @override
   CodegenWorkItem createWorkItem(MemberEntity entity) {
-    return new KernelCodegenWorkItem(entity);
+    return new KernelCodegenWorkItem(_backend, _closedWorld, entity);
   }
 }
 
 class KernelCodegenWorkItem extends CodegenWorkItem {
+  final JavaScriptBackend _backend;
+  final ClosedWorld _closedWorld;
   final MemberEntity element;
   final CodegenRegistry registry;
 
-  KernelCodegenWorkItem(this.element) : registry = new CodegenRegistry(element);
+  KernelCodegenWorkItem(this._backend, this._closedWorld, this.element)
+      : registry = new CodegenRegistry(element);
 
   @override
   WorldImpact run() {
-    // TODO(johnniwinther): Build SSA graph from kernel and run codegen on it.
-    return const WorldImpact();
+    return _backend.codegen(this, _closedWorld);
   }
 }