leipert

// These window.navigator contain language information
// 1. languages -> Array of preferred languages (eg ["en-US", "zh-CN", "ja-JP"]) Firefox^32, Chrome^32
// 2. language  -> Preferred language as String (eg "en-US") Firefox^5, IE^11, Safari, 
//                 Chrome sends Browser UI language
// 3. browserLanguage -> UI Language of IE
// 4. userLanguage    -> Language of Windows Regional Options
// 5. systemLanguage  -> UI Language of Windows
var browserLanguagePropertyKeys = ['languages', 'language', 'browserLanguage', 'userLanguage', 'systemLanguage'];