[webapi] Fix interface name for WebRTC

- Fix interface name
- Failure analysis: The ondatachannel event, onidpvalidationerror event and onidentityresult event cannot be fired. The Identity API extends the RTCPeerConnection interface is not support.

Impacted tests(approved): new 0, update 143, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 111, fail 15, block 17
Merge pull request #680 from yunxliu/yunxliu/webapi/webrtc_modify

[webapi] Fix interface name for WebRTC