Introduce TypedefEntity

pkg/compiler/lib/src/js_emitter/sorter.dart

Index: pkg/compiler/lib/src/js_emitter/sorter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/sorter.dart b/pkg/compiler/lib/src/js_emitter/sorter.dart
index fbe60820a648beca9766340129b19668ed942c49..0443577cf3a56f9d87d910274786174b612a0bba 100644
--- a/pkg/compiler/lib/src/js_emitter/sorter.dart
+++ b/pkg/compiler/lib/src/js_emitter/sorter.dart
@@ -15,6 +15,9 @@ abstract class Sorter {
   /// Returns a sorted list of [classes].
   Iterable<ClassEntity> sortClasses(Iterable<ClassEntity> classes);
 
+  /// Returns a sorted list of [typedefs].
+  Iterable<TypedefEntity> sortTypedefs(Iterable<TypedefEntity> typedefs);
+
   /// Returns a sorted list of [members].
   Iterable<MemberEntity> sortMembers(Iterable<MemberEntity> members);
 }
@@ -33,6 +36,11 @@ class ElementSorter implements Sorter {
   }
 
   @override
+  Iterable<TypedefEntity> sortTypedefs(Iterable<TypedefEntity> typedefs) {
+    return Elements.sortedByPosition(new List.from(typedefs, growable: false));
+  }
+
+  @override
   List<MemberEntity> sortMembers(Iterable<MemberEntity> members) {
     return Elements.sortedByPosition(new List.from(members, growable: false));
   }