Re: Object.assign interaction with __proto__ field.
same way `Object.assign` makes getters own properties, anything else special gets assigned right away, including Symbols.
This is a usually ignored gotta of the issue `Object.assign` could actually cause in the wild, specially with polyfills where WeakMap symbols assigned directly might be passed around.
I'm not sure `__proto__` as key deserves any special treatment, compared to all other little gotchas, but FWIW I'm still for banning `__proto__` from the language through 1 year of browsers warnings and a wide community involvement in getting rid of that little "bomb" ECMA kept in core.
NodeJS got bitten with query strings, developers loading user land JSON can get bitten with `"__proto__": null` and so on and so fort.