Scroll to the right position when going back and show hidden files is enabled.

Instead of emitting the directoryLoadingCompleted signal (via slotCompleted) in
KFileItemModel::setShowHiddenFiles directly, we now call
dispatchPendingItemsToInsert instead.

@Frank: Thanks for your help!

FIXED-IN: 4.13.1
BUG: 332159
REVIEW: 117021

src/kitemviews/kfileitemmodel.cpp

@@ -216,7 +216,7 @@ void KFileItemModel::setShowHiddenFiles(bool show)
     m_dirLister->setShowingDotFiles(show);
     m_dirLister->emitChanges();
     if (show) {
-        slotCompleted();
+        dispatchPendingItemsToInsert();
     }
 }