Remove --promise-extra flag

test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js

Index: test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
diff --git a/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js b/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
index b542bc69dd55ac3f5f62d33d063a332bdc5b2fbb..e5e560b3db9e38370ed9321add85b9c35a5c350b 100644
--- a/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
+++ b/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.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 --promise-extra
+// Flags: --expose-debug-as debug --allow-natives-syntax
 
 // Test debug events when we only listen to uncaught exceptions and
 // there is no catch handler for the to-be-rejected Promise.
@@ -18,7 +18,7 @@ var p = new Promise(function(resolve, reject) {
   resolve();
 });
 
-var q = p.chain(
+var q = p.then(
   function() {
     log.push("reject");
     return Promise.reject(Error("uncaught reject"));  // event