Add access check to JSObject::IsExtensible.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index 2e3fea2bb4282724e3c630c32374bf0210ecd9ee..f871ead87b68e2d84388aa3becf971c388f7cbef 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -310,10 +310,10 @@ RUNTIME_FUNCTION(Runtime_PreventExtensions) {
 
 
 RUNTIME_FUNCTION(Runtime_IsExtensible) {
-  SealHandleScope shs(isolate);
+  HandleScope scope(isolate);
   DCHECK(args.length() == 1);
-  CONVERT_ARG_CHECKED(JSObject, obj, 0);
-  return isolate->heap()->ToBoolean(obj->IsExtensible());
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
+  return isolate->heap()->ToBoolean(JSObject::IsExtensible(obj));
 }