Actual Flow browsertests

These are the tests from qa/browsertests, tweaked for a change from
textarea to text field.
flow_anon.feature passes on both beta labs and ee-flow labs, and one of
flow_logged_in{,_visualeditor}.feature passes according to whether VE is
enabled for Selenium_user.

Change-Id: Ia2b2220979987bb223eb7f0ee272d834f3822dcf