Store CSS token payloads in a variant so each token only carries the
state needed by its type. Keep delimiter, number, hash, string, and
dimension data separate instead of storing every possible payload on
every token.
Use a smaller component-value token for function and block boundary
metadata. These component values only need token type, original source
text, and source positions, so avoid embedding full token payload
storage inside every Function and SimpleBlock.
Shrink CSS source positions to explicit 32-bit counters. Guard the C++
and Rust tokenizer paths against overflow. Add size assertions for the
hot Token and ComponentValue types so future growth is intentional.
DevTools needs rule-level source positions to link applied style
rules back to their source sheets. The parser already tracks token
line and column information, so carry that through qualified rules
and nested declarations when creating CSSRule objects.
Add an abstract image style value for image-set() and parse both the
standard and -webkit-prefixed spellings through the existing <image>
value path. The parser accepts URL and string image candidates,
optional resolution descriptors, and type() filters.
Track attr-taint through substituted component values so image-set()
candidates using attr()-derived URL-producing tokens are rejected when
resolved for URL-using properties.
Update the relevant WPT baselines now that image-set() parsing is
supported in additional value contexts.
Compare `Vector<Parser::ComponentValue>` directly instead of
serializing them into strings first.
This is required for the upcoming changes where we would compare
previous and new sets of custom properties to figure out whether we need
to invalidate descendant elements. Without this change `equals()` would
show up being hot in profiles.
Treating these like any other ComponentValue means not having to convert
between different types of Vector, and that we will be able to use
TokenStream to parse the "argument grammars" of arbitrary substitution
functions.
