Styling was correct because of the explicit dirtiness, but still not fun.
Some things, like dynamic updates to with things like [style~="color"] ~ foo
selectors, were pretty broken, because we didn't take snapshots of those
attributes.
This is a rewrite for how style interfaces with its consumers in order to allow
different representations for an element snapshot.
This also changes the requirements of an element snapshot, requiring them to
only implement MatchAttr, instead of MatchAttrGeneric. This is important for
stylo since implementing MatchAttrGeneric is way more difficult for us given the
atom limitations. This also allows for more performant implementations in the
Gecko side of things.
Fixes#8445
The only attributes I found that we have implemented that uses non-zero
dimenion attributes:
* `width` for `<td>` and `<th>` (table cells)
* `width` for `<table>`
I updated these implementations to use the new non-zero dimension
attribute parsing and added associated regression tests.
Updated string_cache, html5ever, xml5ever and selectors in Cargo.toml files and Cargo.lock.
Removed references to string_cache_plugin.
Import atom! and ns! from string_cache.
Replaced ns!("") by ns!().
Replaced ns!(XML) and co by ns!(xml) and co.
Replaced atom!(foo) by atom!("foo").
Replaced Atom::from_slice by Atom::from.
Replaced atom.as_slice() by &*atom.
