Support typedef type literals

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

Index: pkg/compiler/lib/src/kernel/elements.dart
diff --git a/pkg/compiler/lib/src/kernel/elements.dart b/pkg/compiler/lib/src/kernel/elements.dart
index 241448f65cdd13d1ec32d4f55c2cd6e8fb440b82..5c334fe2a61c6603edbe76fe0b2df7ea3fee10b4 100644
--- a/pkg/compiler/lib/src/kernel/elements.dart
+++ b/pkg/compiler/lib/src/kernel/elements.dart
@@ -32,3 +32,8 @@ abstract class IndexedTypeVariable implements TypeVariableEntity {
   /// Type variable index used for fast lookup in [KernelToElementMapBase].
   int get typeVariableIndex;
 }
+
+abstract class IndexedTypedef implements TypedefEntity {
+  /// Typedef index used for fast lookup in [KernelToElementMapBase].
+  int get typedefIndex;
+}