setPreferredLanguages  
  Set the list of preferred languages.
Set the list of preferred languages, sorted from most desirable to least desirable. The list will be used in the following ways:
- Determining how to build the - Accept-LanguageHTTP header that will be included in the network requests started by the #WebKitWebContext.
- Setting the values of - navigator.languageand- navigator.languages.
- The first item in the list sets the default locale for JavaScript - Intlfunctions.
Parameters
languages
a null-terminated list of language identifiers