Bug 941136 - getUrl not matching webdriver command getCurrentUrl. r=dburns
Bug 941132 - getElementPosition not matching webdriver command. r=dburns
Bug 961792 - Break iteration when browser is found. r=mdas

The iteration used to look up the current window's server-assigned
unique identifier in Marionette continues after the response has been
sent.  This is unnecessary and a potential synchronization problem
because the client only expects a single response.