Tweaks for new Objective-C API.

BUG=

Review URL: https://codereview.webrtc.org/1696673003

Cr-Commit-Position: refs/heads/master@{#11872}
diff --git a/webrtc/api/objc/RTCConfiguration.mm b/webrtc/api/objc/RTCConfiguration.mm
index 2c39118..2d44d01 100644
--- a/webrtc/api/objc/RTCConfiguration.mm
+++ b/webrtc/api/objc/RTCConfiguration.mm
@@ -70,7 +70,7 @@
   webrtc::PeerConnectionInterface::RTCConfiguration nativeConfig;
 
   for (RTCIceServer *iceServer in _iceServers) {
-    nativeConfig.servers.push_back(iceServer.iceServer);
+    nativeConfig.servers.push_back(iceServer.nativeServer);
   }
   nativeConfig.type =
       [[self class] nativeTransportsTypeForTransportPolicy:_iceTransportPolicy];