Refactoring Discarding live preview of interface font

Includes fix for content font as well

Change-Id: Ie97c5d45c6613889975ca6af59c6bd0856d331dc

tests/browser/features/support/pages/panel_page.rb

@@ -32,6 +32,7 @@ class PanelPage
 	a(:trigger_personal, class: 'uls-trigger')
 
 	select(:selected_content_font, id: 'content-font-selector')
+	select(:selected_interface_font, id: 'ui-font-selector')
 
 	select(:select_font_for_interface, id: 'ui-font-selector')
 	select(:select_font_for_content, id: 'content-font-selector')