Fix x.runtimeType for native classes

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

Index: sdk/lib/_internal/compiler/implementation/lib/interceptors.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/interceptors.dart b/sdk/lib/_internal/compiler/implementation/lib/interceptors.dart
index db2b86cdecbb28e43da2145ff922329ce6a8aed9..80bdf07529afd5aa369390095858582270b3bfac 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/interceptors.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/interceptors.dart
@@ -15,14 +15,13 @@ import 'dart:_js_helper' show allMatchesInStringUnchecked,
                               checkNull,
                               checkNum,
                               checkString,
-                              getRuntimeTypeString,
+                              getRuntimeType,
                               regExpGetNative,
                               stringContainsUnchecked,
                               stringLastIndexOfUnchecked,
                               stringReplaceAllFuncUnchecked,
                               stringReplaceAllUnchecked,
                               stringReplaceFirstUnchecked,
-                              TypeImpl,
                               lookupDispatchRecord;
 import 'dart:_foreign_helper' show JS;
 
@@ -210,7 +209,7 @@ abstract class Interceptor {
                                 invocation.namedArguments);
   }
 
-  Type get runtimeType;
+  Type get runtimeType => getRuntimeType(this);
 }
 
 /**