Replacement for ability to "send tab to remote device" as removed from Firefox 29
Sorry for the trouble this is causing you. We initially removed the feature because we didn't know how well it was being used and the UX around it seemed confusing. We intended to improve the feature and release it again soon.

That said, with feedback like yours, and many others, we are reconsidering the decision and will try to get a version of the feature back in Firefox as soon as possible.

You can track some of the discussion here:

https://bugzilla.mozilla.org/show_bug.cgi?id=1002628