Remove obsolete --harmony-promises flag from tests.

test/mjsunit/es6/debug-promises-throw-in-constructor.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: --harmony-promises --expose-debug-as debug
+// Flags: --expose-debug-as debug
 
 // Test debug events when we only listen to uncaught exceptions and
 // an exception is thrown in the the Promise constructor.
 // We expect an Exception debug event with a promise to be triggered.
 
 Debug = debug.Debug;
 
 var step = 0;
 var exception = null;
 
@@ skipping 21 matching lines @@
 
 Debug.setBreakOnUncaughtException();
 Debug.setListener(listener);
 
 var p = new Promise(function(resolve, reject) {
   throw new Error("uncaught");  // event
 });
 
 assertEquals(1, step);
 assertNull(exception);