This can speed up the below micro-bench by 3x and improve JetStream2-tagcloud-SP case by ~2%.

Object.prototype.foo = function() {};
let array = ['a','b','c','d','e'];
let start = Date.now();
for (let i = 0; i < 1e5; i++) {
	for (let j in array) {}
}
console.log(Date.now() - start);

Contributed by tao.pan@intel.com

Change-Id: I44c948c2e4c28b8e42192f36802a5ea0f82bbe25
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2049903Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Shiyu Zhang <shiyu.zhang@intel.com>
Cr-Commit-Position: refs/heads/master@{#66362}