Remove obsolete --harmony-promises flag from tests.

test/mjsunit/es6/mirror-promises.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 --harmony-promises
+// Flags: --expose-debug-as debug
 // Test the mirror object for promises.
 
 function MirrorRefCache(json_refs) {
   var tmp = eval('(' + json_refs + ')');
   this.refs_ = [];
   for (var i = 0; i < tmp.length; i++) {
     this.refs_[tmp[i].handle] = tmp[i];
   }
 }
 
@@ skipping 65 matching lines @@
 
 var m2 = debug.MakeMirror(new Promise(function(resolve, reject) { reject(2) }));
 ip = m2.internalProperties();
 assertEquals("rejected", ip[0].value().value());
 assertEquals(2, ip[1].value().value());
 
 var m3 = debug.MakeMirror(new Promise(function(resolve, reject) { }));
 ip = m3.internalProperties();
 assertEquals("pending", ip[0].value().value());
 assertEquals("undefined", typeof(ip[1].value().value()));