clear the list of pages with text selection when the document changes

svn path=/trunk/KDE/kdegraphics/okular/; revision=755228

ui/pageview.cpp

@@ -686,6 +686,7 @@ void PageView::notifySetup( const QVector< Okular::Page * > & pageSet, int setup
         delete *dIt;
     d->items.clear();
     d->visibleItems.clear();
+    d->pagesWithTextSelection.clear();
     toggleFormWidgets( false );
 
     bool haspages = !pageSet.isEmpty();