Stop worrying about tiny OOMs. Work towards #20449.
While going through these, I also changed the function signature in many
places where returning ThrowCompletionOr<T> is no longer necessary.
We now apply MathML's default user agent style sheet along with other
default styles. This sheet is not mixed in with the other styles in
CSS/Default.css because it is a namespaced stylesheet and so has to
be its own sheet.
We don't yet set the Document's target element in most cases, so this
does not function very well. But that will improve once we *do* set it,
which involves a more complete Navigables implementation.
For now, we parse these, but don't actually consider the namespace when
matching them. `DOM::Element` does not (yet) store attribute namespaces
so we can't check what they are.
Holding the `prefix` as a StringView meant it pointed at string data
held by `token`. `token` gets reassigned shortly afterwards, meaning
`prefix` would hold invalid character data.
This is basically a name with a namespace prefix. It will be used for
adding namespaces to Universal, TagName, and Attribute selectors.
For convenience, this can also optionally parse/store the `*` wildcard
character as the name.
We got some errors while loading https://twinings.co.uk/ about this
interface missing, and it looked fairly simple so I sketched it out.
Note that I did leave some FIXMEs where it's not clear exactly which
metrics we should be returning.
We were already parsing non-function-syntax :host, so let's also do
the :host(...) variant. Note that we don't have matching for these yet.
This fixes many issues on sites generated by Wix, as they often have
selector lists that include some :host() selector, and we'd reject the
entire rule after failing to parse it.
Instead, perform the filtering for each rule as we go. This avoids
creating a separate list of rules, which was ~5% of runtime when
mousing around on the Discord web interface.
...along with `outline-color`, `outline-style`, and `outline-width`.
This re-uses the existing border-painting code, which seems to work well
enough!
This replaces the previous code for drawing focus-outlines, with generic
outline painting for any elements that want it. Focus outlines are now
instead supported by this code in Default.css:
```css
:focus-visible {
outline: auto;
}
```
Don't give up if we can't parse that single value for the property
directly, but let the parsing code carry on and see if we can produce a
CompositeStyleValue.
CSS shouldn't probably check if a MIME type in the 'data:' URL is
correct or not. Every URL gets sent to a ResourceLoader so a client can
just validate if got file with correct media type.
This also makes loading 'data:' URLs in @import work now, as we didn't
have AllowedDataUrlType for stylesheets.
CSSStyleSheet now caches the CSSNamespaceRule for the default namespace,
which is the only one we currently care about. This saves us from
iterating over its list of rules every time we want to know what that
default namespace is.
The spec dictates that `@namespace` rules are only valid near the start
of a stylesheet, so we also take advantage of that to quit searching
for namespaces as soon as we see a non-import rule.
Also renamed `namespace_filter()` to `default_namespace()` since that's
what it actually returns.
This makes github.com/serenityos/serenity snappy again. :^)
The `clip_shrink` optimization in `paint_background()` now also
correctly uses DevicePixels, instead of reducing a DevicePixel rect by
a CSSPixels amount.
