Much like we optimize to_ascii_lowercase.
This also fixes a bug in Servo where attr() rules with an unknown namespace
prefix are parsed, which is wrong.
Now that we have an Element around on cascade, we can stop using the cascade
flags mechanism to pass various element-related state, like "is this element the
root", or "should it use the item-based display fixup".
That fixes handwaviness in the handling of those flags from style reparenting,
and code duplication to handle tricky stuff like :visited.
There are a number of other changes that are worth noticing:
* skip_root_and_item_based_display_fixup is renamed to skip_item_display_fixup:
TElement::is_root() already implies being the document element, which by
definition is not native anonymous and not a pseudo-element.
Thus, you never get fixed-up if your NAC or a pseudo, which is what the code
tried to avoid, so the only fixup with a point is the item one, which is
necessary.
* The pseudo-element probing code was refactored to return early a
Option::<CascadeInputs>::None, which is nicer than what it was doing.
* The visited_links_enabled check has moved to selector-matching time. The rest
of the checks aren't based on whether the element is a link, or are properly
guarded by parent_style.visited_style().is_some() or visited_rules.is_some().
Thus you can transitively infer that no element will end up with a :visited
style, not even from style reparenting.
Anyway, the underlying reason why I want the element in StyleAdjuster is because
we're going to implement an adjustment in there depending on the tag of the
element (converting display: contents to display: none depending on the tag), so
computing that information eagerly, including a hash lookup, wouldn't be nice.
The only reason why we had the `existing_style_for_style_damage` bit is to apply
some optimizations that we don't have anymore.
I still want to reintroduce a few of them, at least for the non-eager
pseudo-element case... But I think I won't need this at all.
This allows us to remove a fair amount of Gecko code too.
Stylo: match both ::placehoder & ::moz-placeholder for placeholder ps…
<!-- Please describe your changes on the following line: -->
The first patch of "Bug 1348490 - stylo: need support for ::-moz-placeholder pseudo element"
Part 2 need to be landed immediately after Part 1 be merged into servo repo:
https://reviewboard.mozilla.org/r/141264/diff/9#index_header
Bugzilla link:
https://bugzilla.mozilla.org/show_bug.cgi?id=1348490
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