Use layerRepaint with visibleRect from Client::map

When map is called we need to repaint the complete area including
decoration shadows (e.g. might be called after unminimize). Therefore
we use a layer repaint with the visibleRect.

BUG: 342085
REVIEW: 121891

client.cpp

@@ -1178,6 +1178,7 @@ void Client::map()
         exportMappingState(NormalState);
     } else
         exportMappingState(IconicState);
+    addLayerRepaint(visibleRect());
 }
 
 /**