Add safeguards against signalling peer-reflexive candidates.
Add safeguards against signalling peer-reflexive candidates.

BUG=4208
R=juberti@google.com

Review URL: https://webrtc-codereview.appspot.com/50799004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9104}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 019087f5bb294d9590b4ed68347ad79d9335ad74

jchavanton/webrtc,jchavanton/webrtc,sippet/webrtc,Alkalyne/webrtctrunk,krieger-od/webrtc,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,sippet/webrtc,jchavanton/webrtc,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,krieger-od/webrtc,Alkalyne/webrtctrunk,jchavanton/webrtc,krieger-od/webrtc,Alkalyne/webrtctrunk,krieger-od/webrtc,jchavanton/webrtc,sippet/webrtc,aleonliao/webrtc-trunk,sippet/webrtc,krieger-od/webrtc,krieger-od/webrtc,Alkalyne/webrtctrunk,sippet/webrtc,jchavanton/webrtc,sippet/webrtc,jchavanton/webrtc,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk