HTMLCollection property names shouldn't be enumerable

[frewsxcv]

<form id="form1" action=""></form>

<script>
var result = [];
for (var p in document.forms) {
  result.push(p);
}
console.log(result);
</script>

Expected output:

0,item,namedItem,length

Actual output:

0,form1,item,namedItem,length

I think this is blocked on #4043

[nox]

#9067

[frewsxcv]

Current failing test

[jdm]

Fixed by #9067.