Get the realtime file's domain correctly. Fixes issue 203.
Some small cleanups for realtime-client-utils.js

R=fraser@google.com

Review URL: https://codereview.appspot.com/58440043

git-svn-id: http://blockly.googlecode.com/svn/trunk@1625 c400ca83-b69d-9dd7-9705-49c6b8615e23