[wrt][XWALK-1670]Add WebRTC testcase
[Detailed commit message (if have)]
Impacted TCs num(designed): New 10, update 0, deleted 0
Unit test platform: [tizen]
Merge pull request #1042 from linshen/shenlin/update/XWALK-1670-WebRTC

[wrt][XWALK-1670]Add WebRTC testcase