Introduce extras export object.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 55b5b3141e1b723f72ce1c5fad5c7ebfd1b38b62..28d007bce57a76e2af104022afa1279f057e5d75 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1467,7 +1467,7 @@ bool Genesis::CompileExtraBuiltin(Isolate* isolate, int index) {
   Handle<String> source_code =
       isolate->bootstrapper()->SourceLookup<ExtraNatives>(index);
   Handle<Object> global = isolate->global_object();
-  Handle<Object> exports = isolate->builtin_exports_object();
+  Handle<Object> exports = isolate->extras_exports_object();
   Handle<Object> args[] = {global, exports};
   return CompileNative(isolate, name, source_code, arraysize(args), args);
 }
@@ -1918,12 +1918,19 @@ bool Genesis::InstallNatives() {
       factory()->NewJSObject(isolate()->object_function());
   JSObject::NormalizeProperties(shared, CLEAR_INOBJECT_PROPERTIES, 16,
                                 "container to share between native scripts");
+
   Handle<JSObject> builtin_exports =
       factory()->NewJSObject(isolate()->object_function());
   JSObject::NormalizeProperties(builtin_exports, CLEAR_INOBJECT_PROPERTIES, 16,
                                 "container to export to experimental natives");
   native_context()->set_builtin_exports_object(*builtin_exports);
 
+  Handle<JSObject> extras_exports =
+      factory()->NewJSObject(isolate()->object_function());
+  JSObject::NormalizeProperties(extras_exports, CLEAR_INOBJECT_PROPERTIES, 2,
+                                "container to export to extra natives");
+  native_context()->set_extras_exports_object(*extras_exports);
+
   if (FLAG_expose_natives_as != NULL) {
     Handle<String> shared_key = factory()->NewStringFromAsciiChecked("shared");
     JSObject::AddProperty(builtins, shared_key, shared, NONE);