QPaintDeviceWindow: Don’t request update on hide

This is not the time to update and the window is
repainted on expose anyway.

Change-Id: I07680a2c351d337e2f35a18b804a03631d5cedc5
Reviewed-by: Jake Petroules <jake.petroules@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>

src/gui/kernel/qpaintdevicewindow.cpp

@@ -187,9 +187,6 @@ void QPaintDeviceWindow::exposeEvent(QExposeEvent *exposeEvent)
         // sometimes relative to the parent, depending on the platform plugin.
         // We require local coords here.
         d->doFlush(QRect(QPoint(0, 0), size()));
-    } else if (!d->dirtyRegion.isEmpty()) {
-        // Updates while non-exposed were ignored. Schedule an update now.
-        requestUpdate();
     }
 }