small cleanup in dart:_runtime

tool/input_sdk/private/ddc_runtime/types.dart

Index: tool/input_sdk/private/ddc_runtime/types.dart
diff --git a/tool/input_sdk/private/ddc_runtime/types.dart b/tool/input_sdk/private/ddc_runtime/types.dart
index 408f7ae5f237d7bb355407a4562612595056ae90..0246c6750e3decf45beb8f9fa4d30548d32e498e 100644
--- a/tool/input_sdk/private/ddc_runtime/types.dart
+++ b/tool/input_sdk/private/ddc_runtime/types.dart
@@ -38,10 +38,10 @@ final metadata = JS('', 'Symbol("metadata")');
 ///  String toString();
 ///
 ///
-final _TypeRepBase = JS('', '$LazyTagged(() => $Type)');
 final TypeRep = JS('', '''
-  class TypeRep extends $_TypeRepBase {
-    get name() {return this.toString();}
+  class TypeRep {
+    get name() { return this.toString(); }
+    get [$_runtimeType]() { return $Type; }
   }
 ''');