Fix sessionStorage initialization code
Fix sessionStorage initialization code

With previous version of this code sessionStorage was never initialized
properly. This breaks travis become.

2947721120/travis-web,2947721120/travis-web,jlrigau/travis-web,Tiger66639/travis-web,fauxton/travis-web,fotinakis/travis-web,jlrigau/travis-web,mjlambert/travis-web,mjlambert/travis-web,travis-ci/travis-web,travis-ci/travis-web,travis-ci/travis-web,mjlambert/travis-web,mjlambert/travis-web,fauxton/travis-web,travis-ci/travis-web,2947721120/travis-web,fauxton/travis-web,Tiger66639/travis-web,fotinakis/travis-web,Tiger66639/travis-web,jlrigau/travis-web,fauxton/travis-web,fotinakis/travis-web,jlrigau/travis-web,fotinakis/travis-web,Tiger66639/travis-web,2947721120/travis-web