[usecase-webapi][XWALK-1473] Fix bug for WebRTC

- The onDataChannel can not be fired on the first channel inChrom, so avoid to use it

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Android]
Unit test result summary: pass 1, fail 0, block 0
[webapi][XWALK-549] Update 11 basic cases for gamepad

- Fail Reason: the gamepad can not connect to the android device, but this sample is passed in chrome 37.

Impacted TCs num: New 0, Update 11, Delete 0
Unit test Platform: Andriod
Unit test result summary: Pass 0, Fail 11, Blocked 0
[usecase-wrt] Delete redundancy file in sample testapp

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 0, deleted 0
Unit test platform: [tizen]
Unit test result summary: xpk sample app install/launch/uninstall Pass 2, Fail 1, Blocked 0
crosswalk:crosswalk-9.37.190.0-0.i686
xpk version can not update:
https://crosswalk-project.org/jira/browse/XWALK-2290
Merge pull request #711 from yunxliu/yunxliu/misc/webrtc_fix

[usecase-webapi][XWALK-1473] Fix bug for WebRTC
Merge pull request #703 from JianfengXu/xujf/gamepad/basic/update

[webapi][XWALK-549] Update 11 basic cases for gamepad
Merge pull request #718 from linshen/misc/wrt-usecase-tizen-tests

[usecase-wrt] Delete redundancy file in sample testapp