Bug 1171400 - Increase screen size to 1280x768 for Travis CI runs on Linux. r=hskupin
Bug 1171400 - Increase screen size to 1280x768 for Travis CI runs on Linux. r=hskupin

armenzg/firefox-ui-tests,galgeek/firefox-ui-tests,utvar/firefox-ui-tests,myrdd/firefox-ui-tests,Motwani/firefox-ui-tests,galgeek/firefox-ui-tests,utvar/firefox-ui-tests,gbrmachado/firefox-ui-tests,gbrmachado/firefox-ui-tests,Motwani/firefox-ui-tests,myrdd/firefox-ui-tests,armenzg/firefox-ui-tests,armenzg/firefox-ui-tests,galgeek/firefox-ui-tests,myrdd/firefox-ui-tests