Remove --promise-extra flag

test/mjsunit/es6/debug-promises/reject-caught-all.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 all exceptions and
 // there is a catch handler for the to-be-rejected Promise.
 // We expect a normal Exception debug event to be triggered.
 
 Debug = debug.Debug;
 
 var log = [];
 var expected_events = 1;
 
 var p = new Promise(function(resolve, reject) {
   log.push("resolve");
   resolve();
 });
 
-var q = p.chain(
+var q = p.then(
   function(value) {
     log.push("reject");
     return Promise.reject(new Error("reject"));
   });
 
 q.catch(
   function(e) {
     assertEquals("reject", e.message);
   });
 
@@ skipping 28 matching lines @@
       }
     } catch (e) {
       %AbortJS(e + "\n" + e.stack);
     }
   }
 
   %EnqueueMicrotask(checkResult);
 }
 
 testDone(0);