Add J-elements

pkg/compiler/lib/src/backend_strategy.dart

Index: pkg/compiler/lib/src/backend_strategy.dart
diff --git a/pkg/compiler/lib/src/backend_strategy.dart b/pkg/compiler/lib/src/backend_strategy.dart
index fe1ebedd7517b5ab46c1ea7e12d914800dc14ade..8236f5c17625087c8878d9d254759bcf41962954 100644
--- a/pkg/compiler/lib/src/backend_strategy.dart
+++ b/pkg/compiler/lib/src/backend_strategy.dart
@@ -4,6 +4,7 @@
 
 library dart2js.backend_strategy;
 
+import 'common/tasks.dart';
 import 'enqueue.dart';
 import 'io/source_information.dart';
 import 'js_backend/js_backend.dart';
@@ -34,8 +35,8 @@ abstract class BackendStrategy {
   /// Creates the [WorkItemBuilder] used by the codegen enqueuer.
   WorkItemBuilder createCodegenWorkItemBuilder(ClosedWorld closedWorld);
 
-  /// Creates the [SsaBuilderTask] used for the element model.
-  SsaBuilderTask createSsaBuilderTask(JavaScriptBackend backend,
+  /// Creates the [SsaBuilder] used for the element model.
+  SsaBuilder createSsaBuilder(CompilerTask task, JavaScriptBackend backend,
       SourceInformationStrategy sourceInformationStrategy);
 
   /// Returns the [SourceInformationStrategy] use for the element model.