coverity#1267638: logically dead code in SwUndo::RedoWithContext()

Change-Id: Iab669a18ed990a23c77b5bb3d6b0a935a8af2c5d

sw/source/core/undo/undobj.cxx

@@ -220,7 +220,6 @@ void SwUndo::RedoWithContext(SfxUndoContext & rContext)
     ::sw::UndoRedoContext *const pContext(
             dynamic_cast< ::sw::UndoRedoContext * >(& rContext));
     assert(pContext);
-    if (!pContext) { return; }
     const UndoRedoRedlineGuard aUndoRedoRedlineGuard(*pContext, *this);
     RedoImpl(*pContext);
 }