Consider storing the associated "parent" Realm in an internal slot

[littledan]

In the HTML integration patch for Realms, HTML keeps track of the parent Realm of each synthetic Realm created in this API as part of a record stored in its [[HostDefined]] field. The parent Realm is used to key off of for various behaviors at the HTML level.

While this mechanism can be defined accurately at the HTML level, it is likely meaningful in other environments as well (cc @jasnell who has been thinking about this for Node.js). So, we should consider defining the parent Realm in a field of the record for synthetic Realms, to facilitate this.

Thanks to @annevk for pointing out this issue.

This is a minor editorial/layering issue that does not block Stage 3 and can be iterated on after it.

[caridy]

sounds good to me! I decided to used [[HostDefined]] because I wasn't sure if such relationship was important for others, but if it is, we should add the new internal slot, and formalize this relationship in the spec itself.

[leobalter]

@littledan can you update on this? Thanks!

[littledan]

My current focus is on completing an initial description of the HTML embedding, which works fine without this editorial change, as I explained. With the editorial variant described in #whatwg/html#6855, the whole "synthetic realm settings object" concept basically exists just to point to the parent realm. So, this change might be a nice cleanup, but it is not urgent.

[caridy]

I believe this is now resolved.

[annevk]

Could you explain how it's resolved? As far as I can tell the HTML PR still uses [[HostDefined]] for this.