As outlined in: https://www.w3.org/TR/selectors-4/#compat
We now do not treat unknown webkit pseudo-elements as invalid at parse
time, and also support serializing these elements.
Fixes: #21959
No functional impact intended. This is just a more complicated way of
writing what we have now.
The goal of this commit is so that we are able to store the 'name' of a
pseudo element for use in serializing 'unknown -webkit-
pseudo-elements', see:
https://www.w3.org/TR/selectors-4/#compat
This is quite awkward, as in pretty much all cases just the selector
type enum is enough, but we will need to cache the name for serializing
these unknown selectors. I can't figure out any reason why we would need
this name anywhere else in the engine, so pretty much everywhere is
still just passing around this raw enum. But this change will allow us
to easily store the name inside of this new struct for when it is needed
for serialization, once those webkit unknown elements are supported by
our engine.
According to the CSS font matching algorithm specification, it is
supposed to be executed for each glyph instead of each text run, as is
currently done. This change partially implements this by having the
font matching algorithm produce a list of fonts against which each
glyph will be tested to find its suitable font.
Now, it becomes possible to have per-glyph fallback fonts: if the
needed glyph is not present in a font, we can check the subsequent
fonts in the list.
Originally, the input was named `tokens`, and we later created a
`tokens_without_whitespace` from the filtered contents of `tokens`.
Since `tokens_without_whitespace` is what we actually want to use while
parsing, let's rename `tokens` -> `unprocessed_tokens` and use the
`tokens` name for the processed ones.
There were two bugs here, one of which hid the other:
- Only one offset would have a value, but we dereferenced both.
- We consumed a token whether it was a valid offset or not.
This removes a performance problem where we'd convert the style sheet's
default namespace from DeprecatedFlyString to FlyString once per rule
during selector matching.
The conversion now happens once, during CSS parse. It should eventually
be removed from there as well, but one step at a time. :^)
