[misc-xwalk] Add test cases of NavigatorLanguage.

-Fail Reason: Cannot read property 'setAcceptLanguages' of undefined at Object

Impacted tests(approved): New 1, Update 0, Delete 0
Unit test platform: [Android]
Unit test result summary: Pass 0, Fail 1, Block 0
=> Check that navigator.language and navigator.languages will expose the accept languages.
Check that languagechange event  (fired on the Window object) will notify of a change in this value.