[misc] update/add tcs for  web-mbat-tests

[Detailed commit message (if have)]
Impacted TCs num(approved): New 1, update 8, deleted 7
Unit test platform: [tizen]
Unit test result summary: Pass 8 , Fail 1, Blocked 0
Crosswalk_WebApp_Update: wgt can not update
BUGID:https://crosswalk-project.org/jira/browse/XWALK-2296
Merge pull request #744 from linshen/wrt/update-mbat

[misc] update/add tcs for  web-mbat-tests