These changes ensure that DiscussionTools is independent of DOM
library choice, and will not break if/when Parsoid switches to an
alternate (more standards-compliant) DOM library.
We run `phan` against the Dodo standards-compliant DOM library,
so this ends up flagging uses of non-standard PHP extensions to
the DOM. These will be suppressed for now with a "Nonstandard DOM"
comment that can be grepped for, since they will eventually
will need to be rewritten or worked around.
Most frequent issues:
* Node::nodeValue and Node::textContent and Element::getAttribute()
can return null in a spec-compliant implementation. Add `?? ''` to
make spec-compliant results consistent w/ what PHP returns.
* DOMXPath doesn't accept anything except DOMDocument. These uses
should be replaced with DOMCompat::querySelectorAll() or similar
(which end up using DOMXPath under the covers for DOMDocument any way,
but are implemented more efficiently in a spec-compliant
implementation).
* A couple of times we have code like:
`while ($node->firstChild!==null) { $node = $node->firstChild; }`
and phan's analysis isn't strong enough to determine that $node is still
non-null after the while. This same issue should appear with DOMDocument
but phan doesn't complain for some reason.
One apparently legit issue:
* Node::insertBefore() is once called in a funny way which leans on
the fact that the second option is optional in PHP. This seems to be
a workaround for an ancient PHP bug, and can probably be safely
removed.
Bug: T287611
Bug: T217867
Change-Id: I3c4f41c3819770f85d68157c9f690d650b7266a3
This is similar to what the JS version does.
The TreeWalker and NodeFilter classes are adapted from
https://github.com/Krinkle/dom-TreeWalker-polyfill
(MIT license).
This makes #getComments twice as fast on en-big-oldparser.html
Change-Id: I2441f33e6e7bad753ac830d277e6a2e81ee8c93d
