forcepoint#45 object may not be a EMFPPen

Change-Id: Ifb5c17e13faf6e9d246e1668ef7916957a5296b6
Reviewed-on: https://gerrit.libreoffice.org/55677Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

drawinglayer/source/tools/emfphelperdata.cxx

@@ -389,7 +389,7 @@ namespace emfplushelper
 
     void EmfPlusHelperData::EMFPPlusDrawPolygon(const ::basegfx::B2DPolyPolygon& polygon, sal_uInt32 penIndex)
     {
-        const EMFPPen* pen = static_cast<EMFPPen*>(maEMFPObjects[penIndex & 0xff].get());
+        const EMFPPen* pen = dynamic_cast<EMFPPen*>(maEMFPObjects[penIndex & 0xff].get());
         SAL_WARN_IF(!pen, "drawinglayer", "emf+ missing pen");
 
         if (pen && polygon.count())