Update structured cloning for recent HTML changes

[domenic]

whatwg/html@97d644c changed structured cloning significantly. I am not sure what the correct changes are here myself; it will likely require coordination with the File API folks.

[annevk]

So now close() is gone we might be able to not clone at all and just pass the reference from the blob store along since code can no longer change the state of a blob object.

Should maybe make sure File API keeps that invariant alive though.

[domenic]

Oh interesting. If so also let's be sure to revise the two notes in the HTML Standard about how URL parsing uses StructuredSerialize.

[annevk]

So as long as blob URLs also work for MediaStream and MediaSource this is not going to work, since those two objects are mutable.

[annevk]

However, those two objects cannot be serialized/deserialized (though MediaStream can be cloned through a locally defined operation). Good times. Per w3c/mediacapture-main#404 blob URLs might go away for MediaStream.

I guess we should just accept that those objects are mutable and what you get depends on when you start reading them...