[usecase-webapi][XWALK-2287] Fix bug for MediaQueries

- Update the description for the test

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Andriod]
Unit test result summary: pass 1, fail 0, block 0
This usecase can be tested on multiple platforms. We do not know the device aspect ratio and the device height in pixel what user use to test. So user must know his device aspect ratio and the device height in pixel. Aother, if use <ol>, the layout of the title and the button will be affected.