Removed unused private properties

Digging through some of the Gridview code I found that these two
properties aren't being used at all. Maybe they had a place in there to
begin with but not anymore?

Doesn't make much sense anymore being that each cell can have their own
dimension.

modules/mojox/gridview.monkey2

@@ -124,8 +124,6 @@ Class GridView Extends View
 		End
 	End
 	
-	Field _cellw:Int
-	Field _cellh:Int
 	Field _gridw:Int
 	Field _gridh:Int
 	Field _cells:=New Stack<Cell>