Array: includes, find, findIndex, some, every, reverse via
tail-recursive helpers.
Object: hasOwnProperty, isPrototypeOf, propertyIsEnumerable,
toString, valueOf, toLocaleString fallback in js-invoke-method
when js-get-prop returns undefined. Lets o.hasOwnProperty('k')
work on plain dicts.
376/378 unit (+13), 148/148 slice unchanged.