Disable non-standard Promise functions in staging

test/mjsunit/es6/debug-promises/throw-with-throw-in-reject.js

Index: test/mjsunit/es6/debug-promises/throw-with-throw-in-reject.js
diff --git a/test/mjsunit/es6/debug-promises/throw-with-throw-in-reject.js b/test/mjsunit/es6/debug-promises/throw-with-throw-in-reject.js
index bd39a155ccb60099178e6ea755a68deb4af0304b..349d014701cbd50e15564eb580619f355f440e74 100644
--- a/test/mjsunit/es6/debug-promises/throw-with-throw-in-reject.js
+++ b/test/mjsunit/es6/debug-promises/throw-with-throw-in-reject.js
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax
+// Flags: --expose-debug-as debug --allow-natives-syntax --promise-extra
 
 // Test debug events when an exception is thrown inside a Promise, which is
 // caught by a custom promise, which throws a new exception in its reject