dynamic_cast followed by static_cast

Change-Id: I931ed8945b4af713ead42e0eca0bb5fb6cb07d9c
Reviewed-on: https://gerrit.libreoffice.org/58759Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sw/source/core/layout/ssfrm.cxx

@@ -475,9 +475,9 @@ void SwLayoutFrame::DestroyImpl()
                 const size_t nCnt = pFrame->GetDrawObjs()->size();
                 // #i28701#
                 SwAnchoredObject* pAnchoredObj = (*pFrame->GetDrawObjs())[0];
-                if ( dynamic_cast< const SwFlyFrame *>( pAnchoredObj ) !=  nullptr )
+                if (SwFlyFrame* pFlyFrame = dynamic_cast<SwFlyFrame*>(pAnchoredObj))
                 {
-                    SwFrame::DestroyFrame(static_cast<SwFlyFrame*>(pAnchoredObj));
+                    SwFrame::DestroyFrame(pFlyFrame);
                     assert(!pFrame->GetDrawObjs() || nCnt > pFrame->GetDrawObjs()->size());
                 }
                 else