Remove --promise-extra flag

test/mjsunit/es6/debug-promises/reject-after-resolve.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // 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 listen to uncaught exceptions and
 // the Promise is rejected in a chained closure after it has been resolved.
 // We expect no Exception debug event to be triggered.
 
 Debug = debug.Debug;
 
 var log = [];
 
 var p = new Promise(function(resolve, reject) {
   log.push("resolve");
   resolve(reject);
 });
 
-var q = p.chain(
+var q = p.then(
   function(value) {
     assertEquals(["resolve", "end main"], log);
     value(new Error("reject"));
   });
 
 function listener(event, exec_state, event_data, data) {
   try {
     assertTrue(event != Debug.DebugEvent.Exception);
   } catch (e) {
     %AbortJS(e + "\n" + e.stack);
   }
 }
 
 Debug.setBreakOnException();
 Debug.setListener(listener);
 
 log.push("end main");