Fix `toggleDrawer` disables scrolling on Layout with `fixedHeader`
Fix `toggleDrawer` disables scrolling on Layout with `fixedHeader`

Changed line 825 now causes correct behaviour on unchanged line 870.

Fix #136.

vipentti/elm-mdl,hakonrossebo/elm-mdl,aforemny/elm-mdc,hakonrossebo/elm-mdl,vipentti/elm-mdl