Equality fails for objects with no prototype

[ClaireNeveu]

Some javascript libraries expose objects without prototypes created using Object.create(null). compare from caml_obj fails on these because it calls hasOwnProperty directly on the object instead of using Object.prototype.hasOwnProperty.call

Here's a very small reproduction:

let prototype: Js.t<{"a": int}> = {"a": 5}
let noPrototype: Js.t<{"a": int}> = %raw(`(function(){
  let o = Object.create(null);
  o.a = 5;
  return o;
})()`)

prototype == noPrototype

This can be worked around if the foreign object can be converted to JSON and back but it'd be nice if this worked out of the box since there's an easy fix.