Phonertc demo works in android but not working in browser

I have follow to http://stackoverflow.com/questions/26410915/phonertc-demo-application.
so android is working well.

then I have run
cordova platform add browser --usegit
grunt build --force
cordova run browser

and login view is displayed. I can success login. and call success.
but browser console out "but vendor.js:4 TypeError: Cannot read property 'receiveMessage' of undefined"

then I can not connect with other browser