JS: fix a FN for prototype polluting function query

[kaeluka]

Fixes another FN from #8846 (CVE-2021-23574).

The bottom line is, that using iteration like this used to work:

function forEachPropNoTempVar(obj, callback) {
    const keys = Object.keys(obj)
    const len = keys.length
    for (let i = 0; i < len; i++) {
        const key = keys[i];
        callback(key, obj[key])
    }
}

But iteration like that did not (now fixed):

function forEachPropNoTempVar(obj, callback) {
    const keys = Object.keys(obj)
    const len = keys.length
    for (let i = 0; i < len; i++) {
        // no local variable used
        callback(keys[i], obj[keys[i]])
    }
}

[kaeluka]

The experiments came back; looks all good.

[erik-krogh]

👍