"Parse JSON to Infra" algorithms shouldn't require a current JS realm about infra

[annevk]

We could also setup a bare bones synthetic environment. Not sure what I'd prefer.

@syg @ljharb did you all think about this at some point perhaps?

[domenic]

IndexedDB does "a user agent-defined Realm", albeit with structured clone which is a bit different since it takes a realm argument instead of using the ambient current realm: https://w3c.github.io/IndexedDB/#add-or-put

I think we can do the same thing; just push a user agent defined realm on the stack, and pop it at the end.

[domenic]

If we did want to refactor to not have any realm dependency, we could basically pull out steps 4-5 of https://tc39.es/ecma262/#sec-json.parse , and then crawl the ParseNode tree instead of our current strategy of crawling the object tree. I have a lot less experience working with ParseNodes in specs, but it's at least conceivable that this is about the same amount of work as what we currently do?

[ljharb]

@annevk tbh i have absolutely no idea what "infra" is and why there would ever not be a Realm when JS is executing.

[annevk]

For some callers another problem here is that this algorithm can throw, but I think some callers also depend on that. So maybe that requires its own wrapper.