Explain more of "create and initialize a Document object"

[domenic]

This should help address some of the questions that came up in #6491. No normative changes.

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/browsing-the-web.html ( diff )

[rakina]

Thanks, this looks good to me! This does not cover initial about:blank => about:blank#foo => same-origin document - it probably makes sense to keep the same Window too in this case, but that's a behavior change so we should discuss it in #6491.

[annevk]

This seems fine, but Window's associated Document not being a Document is a bug of sorts and this further highlights that. (I haven't looked at all the algorithms that get invoked between these two points, but it does not seem robust.)

[domenic]

Yeah, I had a similar discussion with @domfarolino. I argue that it's fine for things to be in a not-fully-initialized/invariants-broken state for a bit as we go through the algorithms. In between those two steps it's just a bunch of syncing up of Document/Window/browsing context/session history, culminating in everything being ready for "set the active document" to finalize the relationship.

[annevk]

I'm just worried that one of those algorithms we invoke inbetween ends up poking at it directly.