Remove stun server in webrtc peerconnection.js

Remove stun server in webrtc peerconnection.js

Specifying the stun server which can't be accessed in the test environment disallows WebRTC to generate loopback candidates. The current logic for generating loopback candidates is that if the permission is denied, the RtcConfiguration has to be null or undefined.

This prevents the turning on of IP Permission check as in https://codereview.chromium.org/1380323005/

BUG=538815
Committed: https://crrev.com/da45e6c11a011a33795fa899133667aa8642caca
Cr-Commit-Position: refs/heads/master@{#353113}

[guoweis_left_chromium, 2015-10-07 16:56:34]

guoweis@chromium.org changed reviewers:
+ phoglund@chromium.org, thakis@chromium.org

[phoglund_chromium, 2015-10-08 07:41:01]

lgtm

[guoweis_left_chromium, 2015-10-08 16:55:08]

The CQ bit was checked by guoweis@chromium.org

[commit-bot: I haz the power, 2015-10-08 16:56:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1395553003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1395553003/1

[guoweis_left_chromium, 2015-10-08 17:15:47]

The CQ bit was unchecked by guoweis@chromium.org

[guoweis_left_chromium, 2015-10-08 17:16:12]

The CQ bit was checked by guoweis@chromium.org

[guoweis_left_chromium, 2015-10-08 17:16:46]

The CQ bit was unchecked by guoweis@chromium.org

[commit-bot: I haz the power, 2015-10-08 17:17:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1395553003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1395553003/1

[guoweis_left_chromium, 2015-10-08 17:20:13]

The CQ bit was checked by guoweis@chromium.org

[commit-bot: I haz the power, 2015-10-08 17:21:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1395553003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1395553003/1

[commit-bot: I haz the power, 2015-10-08 18:51:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-08 18:53:32]

Patchset 1 (id:??) landed as
https://crrev.com/da45e6c11a011a33795fa899133667aa8642caca
Cr-Commit-Position: refs/heads/master@{#353113}