Introduce TypedefEntity

pkg/compiler/lib/src/js_model/js_strategy.dart

Index: pkg/compiler/lib/src/js_model/js_strategy.dart
diff --git a/pkg/compiler/lib/src/js_model/js_strategy.dart b/pkg/compiler/lib/src/js_model/js_strategy.dart
index 94215a63b5411dff60d47ba7fad2c12a71baa0f1..be47ef04dc57bf40b95e9f1771d29dbb939313ff 100644
--- a/pkg/compiler/lib/src/js_model/js_strategy.dart
+++ b/pkg/compiler/lib/src/js_model/js_strategy.dart
@@ -10,7 +10,7 @@ import '../common/tasks.dart';
 import '../common_elements.dart';
 import '../compiler.dart';
 import '../constants/constant_system.dart';
-import '../elements/elements.dart' show ClassElement, TypedefElement;
+import '../elements/elements.dart' show ClassElement;
 import '../elements/entities.dart';
 import '../elements/types.dart';
 import '../enqueue.dart';
@@ -297,7 +297,7 @@ class JsBackendStrategy implements KernelBackendStrategy {
         mixinUses: mixinUses,
         typesImplementedBySubclasses: typesImplementedBySubclasses,
         // TODO(johnniwinther): Support this:
-        allTypedefs: new ImmutableEmptySet<TypedefElement>());
+        allTypedefs: new ImmutableEmptySet<TypedefEntity>());
   }
 
   @override
@@ -360,7 +360,7 @@ class JsClosedWorld extends ClosedWorldBase with KernelClosedWorldMixin {
       Iterable<ClassEntity> liveNativeClasses,
       Iterable<MemberEntity> liveInstanceMembers,
       Iterable<MemberEntity> assignedInstanceMembers,
-      Set<TypedefElement> allTypedefs,
+      Set<TypedefEntity> allTypedefs,
       Map<ClassEntity, Set<ClassEntity>> mixinUses,
       Map<ClassEntity, Set<ClassEntity>> typesImplementedBySubclasses,
       Map<ClassEntity, ClassHierarchyNode> classHierarchyNodes,