Fix util to adjust string for locale direction

ios/chrome/browser/ui/util/i18n_string.mm

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/ui/util/i18n_string.h"
 
 #include "base/i18n/rtl.h"
 #include "base/strings/string16.h"
 #include "base/strings/sys_string_conversions.h"
 
 NSString* AdjustStringForLocaleDirection(NSString* text) {
   base::string16 converted_text = base::SysNSStringToUTF16(text);
   bool has_changed =
       base::i18n::AdjustStringForLocaleDirection(&converted_text);
   if (has_changed) {
     return base::SysUTF16ToNSString(converted_text);
   }
-  return text;
+  return [[text copy] autorelease];
 }