Always show scrollbars when a div can be scrolled (#863)
Always show scrollbars when a div can be scrolled (#863)

* Always show a scrollbar when divs can be scrolled, fixes #814

* minor

playi/pxt,Microsoft/pxt,switchinnovations/pxt,switch-education/pxt,playi/pxt,switchinnovations/pxt,switchinnovations/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,switchinnovations/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt,Microsoft/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt