Make sure the test holds a reference of secondDataChannel.

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

Index: content/test/data/media/peerconnection-call.html
diff --git a/content/test/data/media/peerconnection-call.html b/content/test/data/media/peerconnection-call.html
index 345d0ea45eb713b45716a2405d69496afc6bbc2b..2912cd41f8ceea302efe4b773f838a8577d711f8 100644
--- a/content/test/data/media/peerconnection-call.html
+++ b/content/test/data/media/peerconnection-call.html
@@ -615,7 +615,8 @@
 
     // Event handler for when |gSecondConnection| receive a new dataChannel.
     gSecondConnection.ondatachannel = function (event) {
-      var secondDataChannel = event.channel;
+      // Make secondDataChannel global to make sure it's not gc'd.
+      secondDataChannel = event.channel;
 
       // When |secondDataChannel| receive a message, send a message back.
       secondDataChannel.onmessage = function(event) {
@@ -653,7 +654,8 @@
 
     // Event handler for when |gSecondConnection| receive a new dataChannel.
     gSecondConnection.ondatachannel = function (event) {
-      var secondDataChannel = event.channel;
+      // Make secondDataChannel global to make sure it's not gc'd.
+      secondDataChannel = event.channel;
       secondDataChannel.onopen = function() {
         secondDataChannel.send(sendDataString);
       }