[behavior][XWALK-1565]Add powerfailure testcase for behavior

[Detailed commit message (if have)]
Impacted TCs num(designed): New 1, update 0, deleted 0
Unit test platform: [tizen]
[sample] Remove unreferenced style file
Merge pull request #836 from zqzhang/test.css

[sample] Remove unreferenced style file
Merge pull request #835 from linshen/wrt/shenlin/movetctbehaviorpowerfailure

[behavior][XWALK-1565]Add powerfailure testcase for behavior