Remove unneeded forward declare

nyalldawson · nyalldawson · commit a0d46d12c13a · 2018-10-17T06:19:06.000+10:00
diff --git a/src/app/qgsstatisticalsummarydockwidget.h b/src/app/qgsstatisticalsummarydockwidget.h
@@ -33,7 +33,6 @@ class QModelIndex;
 class QgsDockBrowserTreeView;
 class QgsLayerItem;
 class QgsDataItem;
-class QgsBrowserTreeFilterProxyModel;
 class QgsVectorLayer;
 
 /**
