Obsolete. The JS pipeline was disabled in IE8 in 2016.
The code in question appears to no longer be a good candidate for using Object.keys() since that it wants isn't an array but a lookup table. Those would make more sense to generate with the for-loop (as it does today) then to create, fill and iterate an array, and then to create, iterate and fill an object. (the code also wouldn't be simpler).