Using static_cast instead of dynamic_cast:

This is just a downcast and the object is always expected
to be SvXMLImportContext.

Change-Id: I755b6b366144d86104b1284fabe3dba74fb54452
Reviewed-on: https://gerrit.libreoffice.org/41063Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

xmloff/source/core/xmlimp.cxx

@@ -843,8 +843,9 @@ void SAL_CALL SvXMLImport::startFastElement (sal_Int32 Element,
         maNamespaceHandler->addNSDeclAttributes( maNamespaceAttrList );
         std::unique_ptr<SvXMLNamespaceMap> pRewindMap(
                 processNSAttributes( maNamespaceAttrList.get() ));
-        SvXMLImportContext *pContext = dynamic_cast<SvXMLImportContext*>( xContext.get() );
-        if( pContext && pRewindMap )
+        assert( dynamic_cast<SvXMLImportContext*>( xContext.get() ) != nullptr );
+        SvXMLImportContext *pContext = static_cast<SvXMLImportContext*>( xContext.get() );
+        if (pRewindMap)
             pContext->PutRewindMap(std::move(pRewindMap));
         maContexts.push(pContext);
     }