Native context: do not put public symbols and flags on the js builtins object.

src/bootstrapper.h

Index: src/bootstrapper.h
diff --git a/src/bootstrapper.h b/src/bootstrapper.h
index 0e1d0c992d26108593fb882828a364d8b373b05d..b69a73acf7f35e78f57c39a1f4a384b5d93e94e6 100644
--- a/src/bootstrapper.h
+++ b/src/bootstrapper.h
@@ -119,8 +119,9 @@ class Bootstrapper final {
   static bool CompileCodeStubBuiltin(Isolate* isolate, int index);
   static bool InstallCodeStubNatives(Isolate* isolate);
 
-  static void ExportPrivateSymbols(Isolate* isolate,
-                                   Handle<JSObject> container);
+  static void ExportFromRuntime(Isolate* isolate, Handle<JSObject> container);
+  static void ExportExperimentalFromRuntime(Isolate* isolate,
+                                            Handle<JSObject> container);
 
  private:
   Isolate* isolate_;