Bug 695252. When switching cards in a deck we don't need to purge all thebes layer contents. r=roc

layout/xul/base/src/nsDeckFrame.cpp

@@ -177,8 +177,7 @@ nsDeckFrame::IndexChanged(nsPresContext* aPresContext)
     return;
 
   // redraw
-  nsBoxLayoutState state(aPresContext);
-  Redraw(state);
+  InvalidateOverflowRect();
 
   // hide the currently showing box
   nsIBox* currentBox = GetSelectedBox();