Revert "Revert "Fix x.runtimeType for native classes""

sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index c505a4728d4f7604d76d8d2ac838e5b62bbc522c..35c4dc630a650daab6088fa5f4713d403cda11c2 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -177,6 +177,8 @@ abstract class Backend {
   ClassElement get boolImplementation => compiler.boolClass;
   ClassElement get nullImplementation => compiler.nullClass;
 
+  ClassElement defaultSuperclass(ClassElement element) => compiler.objectClass;
+
   bool isDefaultNoSuchMethodImplementation(Element element) {
     assert(element.name == Compiler.NO_SUCH_METHOD);
     ClassElement classElement = element.getEnclosingClass();