[behavior][XWALK-2146] Fix the bug that the 'Pass' button is disabled when click the 'Cancle CSS FullScreen' button.

Impacted tests(approved): New 0, Update 1, Delete 0
Unit test platform: [TIZEN IVI]
Unit test result summary: Pass 1, Fail 0, Block 0
Merge pull request #503 from minxhuang/hm/behavior/FullScreen

 [behavior][XWALK-2146] Fix the bug that the 'Pass' button is disabled when click the 'Cancle CSS FullScreen' button.