loops: Rewrite last false `reduce`, with `objectFromEntries`.
loops: Rewrite last false `reduce`, with `objectFromEntries`.

Huzzah!

There are a handful of calls to `reduce` remaining, in two files.
They're all legit `reduce`, though: the reducer function is a
pure function that doesn't rely on mutation to do its work.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile