Always log SDP for WebRTC tests.

We removed SDP logging earlier because it was bloating bot logs, but
nowadays logs only get printed for failing tests, and SDP information
is very useful to debug for instance webrtc:4570.

BUG=webrtc:4570,484826,479093

Review URL: https://codereview.chromium.org/1124323005

Cr-Commit-Position: refs/heads/master@{#330722}

content/test/data/media/peerconnection-call.html

@@ -793,6 +793,7 @@
 
   function onOfferCreated(offer, caller, callee) {
     offer.sdp = maybeForceIsac16K(transformSdp(offer.sdp));
+    console.log('Offer:\n' + offer.sdp);
     caller.setLocalDescription(offer, function() {
       assertEquals('have-local-offer', caller.signalingState);
       receiveOffer(offer.sdp, caller, callee);
@@ -869,6 +870,7 @@
 
   function onAnswerCreated(answer, caller, callee) {
     answer.sdp = maybeForceIsac16K(transformSdp(answer.sdp));
+    console.log('Answer:\n' + answer.sdp);
     callee.setLocalDescription(answer,
                                function () {
                                  assertEquals('stable', callee.signalingState);