SplObjectStorage compatibility
SplObjectStorage compatibility

- `_index` is not var_dumped or printed or exported

peachpiecompiler/peachpie,iolevel/peachpie-concept,iolevel/peachpie-concept,peachpiecompiler/peachpie,iolevel/peachpie,iolevel/peachpie,iolevel/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept