Bug 728686 - JS_NewPropertyIterator shouldn't disable IGC (r=igor)

js/src/jsapi.cpp

@@ -4284,7 +4284,7 @@ prop_iter_trace(JSTracer *trc, JSObject *obj)
 
 static Class prop_iter_class = {
     "PropertyIterator",
-    JSCLASS_HAS_PRIVATE | JSCLASS_HAS_RESERVED_SLOTS(1),
+    JSCLASS_HAS_PRIVATE | JSCLASS_IMPLEMENTS_BARRIERS | JSCLASS_HAS_RESERVED_SLOTS(1),
     JS_PropertyStub,         /* addProperty */
     JS_PropertyStub,         /* delProperty */
     JS_PropertyStub,         /* getProperty */