Remove the unused dividerHidden property of GraySplitView.
Remove the unused dividerHidden property of GraySplitView.

atom/brightray,lakshmi-srinivas/brightray,hokein/brightray,brave/brightray,deepak1556/brightray,lakshmi-srinivas/brightray,tejaspathak/brightray,atom/brightray,paulcbetts/brightray,paulcbetts/brightray,hokein/brightray,brave/brightray,bbondy/brightray,lakshmi-srinivas/brightray,deepak1556/brightray,tejaspathak/brightray,bbondy/brightray