[JSC] Generic iterator protocol function should be invisible to Function's caller getter

This code should have returned function foo instead of null

function foo(arr) {
    return [...arr];
}

let obj = {};
obj[Symbol.iterator] = function bar () {
    alert(arguments.callee.caller);
    return {
        next() { return { done: true }; }
    };
};
foo(obj);

[Radar WebKit Bug Importer]

<rdar://problem/96253786>

[Yusuke Suzuki]

Pull request: https://github.com/WebKit/WebKit/pull/2498

[EWS]

Committed 252578@main (1a1af3bd846d): <https://commits.webkit.org/252578@main>

Reviewed commits have been landed. Closing PR #2498 and removing active labels.