Introduce TypedefEntity

pkg/compiler/lib/src/elements/entities.dart

Index: pkg/compiler/lib/src/elements/entities.dart
diff --git a/pkg/compiler/lib/src/elements/entities.dart b/pkg/compiler/lib/src/elements/entities.dart
index 80e8489fd8ed9dba8458886644bb15fa6e82443c..2e89c2b47380d2b2326a943ef7138d125cffedaf 100644
--- a/pkg/compiler/lib/src/elements/entities.dart
+++ b/pkg/compiler/lib/src/elements/entities.dart
@@ -51,6 +51,10 @@ abstract class ClassEntity extends Entity {
   bool get isAbstract;
 }
 
+abstract class TypedefEntity extends Entity {
+  LibraryEntity get library;
+}
+
 abstract class TypeVariableEntity extends Entity {
   /// The class or generic method that declared this type variable.
   Entity get typeDeclaration;