[misc-xwalk] Integrate tests 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
Merge pull request #635 from minxhuang/hm/misc/xwalk-system/Navigator_Language

[misc-xwalk] Integrate tests of NavigatorLanguage.