A document is not a browsing context container by definition so the loop is unneeded.

This removes the manifest attribute on the html element, the text/cache-manifest format, the integration of application caches with navigation, the monkey patching of what is now Fetch, and the window.applicationCache API.

Closes #151 and closes #5505.

This regressed in 90a60b2, which
accidentally removed the step which lets the recursion continue by
setting the current object to the appropriate "owner" document. Even
though control group owner objects are removed, we still need to
traverse up to the document in focus chain computation.

While here, this rewrites the algorithm to use a loop instead of a goto
for clarity.

Closes #6161.

See #5958 (comment).

Closes #6139.

Fixes #2455 by passing the creation URL to "set up a window
environment's settings object", instead of having it attempt to grab the
creation URL from the not-yet-created Document object.

The later comments in #2455 discuss some followup work we could do to
clarify the Document/Window relationship, but that is left for a future
commit.

This also removes the XXX box mentioned in #2688, since Documents are
nowadays created after Windows in the spec.

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