--- a/js/ipc/WrapperAnswer.cpp
+++ b/js/ipc/WrapperAnswer.cpp
@@ -215,69 +215,64 @@ WrapperAnswer::RecvDelete(const ObjectId
 
     ObjectOpResult success;
     if (!JS_DeletePropertyById(cx, obj, id, success))
         return fail(jsapi, rs);
     return ok(rs, success);
 }
 
 bool
-WrapperAnswer::RecvHas(const ObjectId& objId, const JSIDVariant& idVar, ReturnStatus* rs, bool* bp)
+WrapperAnswer::RecvHas(const ObjectId& objId, const JSIDVariant& idVar, ReturnStatus* rs,
+                       bool* foundp)
 {
     AutoJSAPI jsapi;
     if (NS_WARN_IF(!jsapi.Init(scopeForTargetObjects())))
         return false;
     jsapi.TakeOwnershipOfErrorReporting();
     JSContext* cx = jsapi.cx();
-    *bp = false;
+    *foundp = false;
 
     RootedObject obj(cx, findObjectById(cx, objId));
     if (!obj)
         return fail(jsapi, rs);
 
     LOG("%s.has(%s)", ReceiverObj(objId), Identifier(idVar));
 
     RootedId id(cx);
     if (!fromJSIDVariant(cx, idVar, &id))
         return fail(jsapi, rs);
 
-    bool found;
-    if (!JS_HasPropertyById(cx, obj, id, &found))
+    if (!JS_HasPropertyById(cx, obj, id, foundp))
         return fail(jsapi, rs);
-    *bp = !!found;
-
     return ok(rs);
 }
 
 bool
 WrapperAnswer::RecvHasOwn(const ObjectId& objId, const JSIDVariant& idVar, ReturnStatus* rs,
-                          bool* bp)
+                          bool* foundp)
 {
     AutoJSAPI jsapi;
     if (NS_WARN_IF(!jsapi.Init(scopeForTargetObjects())))
         return false;
     jsapi.TakeOwnershipOfErrorReporting();
     JSContext* cx = jsapi.cx();
-    *bp = false;
+    *foundp = false;
 
     RootedObject obj(cx, findObjectById(cx, objId));
     if (!obj)
         return fail(jsapi, rs);
 
     LOG("%s.hasOwn(%s)", ReceiverObj(objId), Identifier(idVar));
 
     RootedId id(cx);
     if (!fromJSIDVariant(cx, idVar, &id))
         return fail(jsapi, rs);
 
-    Rooted<JSPropertyDescriptor> desc(cx);
-    if (!JS_GetPropertyDescriptorById(cx, obj, id, &desc))
+    if (!JS_HasOwnPropertyById(cx, obj, id, foundp))
         return fail(jsapi, rs);
-    *bp = (desc.object() == obj);
-
     return ok(rs);
 }
 
 bool
 WrapperAnswer::RecvGet(const ObjectId& objId, const ObjectVariant& receiverVar,
                        const JSIDVariant& idVar, ReturnStatus* rs, JSVariant* result)
 {
     // We may run scripted getters.

--- a/js/ipc/WrapperAnswer.h
+++ b/js/ipc/WrapperAnswer.h
@@ -31,19 +31,19 @@ class WrapperAnswer : public virtual Jav
                                       const JSIDVariant& id,
                                       ReturnStatus* rs,
                                       PPropertyDescriptor* out);
     bool RecvDefineProperty(const ObjectId& objId, const JSIDVariant& id,
                             const PPropertyDescriptor& flags, ReturnStatus* rs);
     bool RecvDelete(const ObjectId& objId, const JSIDVariant& id, ReturnStatus* rs);
 
     bool RecvHas(const ObjectId& objId, const JSIDVariant& id,
-                 ReturnStatus* rs, bool* bp);
+                 ReturnStatus* rs, bool* foundp);
     bool RecvHasOwn(const ObjectId& objId, const JSIDVariant& id,
-                    ReturnStatus* rs, bool* bp);
+                    ReturnStatus* rs, bool* foundp);
     bool RecvGet(const ObjectId& objId, const ObjectVariant& receiverVar,
                  const JSIDVariant& id,
                  ReturnStatus* rs, JSVariant* result);
     bool RecvSet(const ObjectId& objId, const JSIDVariant& id, const JSVariant& value,
                  const JSVariant& receiverVar, ReturnStatus* rs);
 
     bool RecvIsExtensible(const ObjectId& objId, ReturnStatus* rs,
                           bool* result);