Move Taffy to 0.15 and Stylo to 0.22 using fixed fork revisions, with the
matching stylo_taffy adapter. Upgrade cssparser and the production HTML/XML
parsers while preserving the vendored XML behavior.
Adapt sizing inputs, baselines, grid positions, overflow and out-of-flow
ownership. Preserve font-stretch CSSOM compatibility and intrinsic sizing
through nested atomic inline probes.
Validation: root cargo fmt --all; strict workspace/all-target/all-feature
Clippy; Nextest 20280 passed, 18 skipped; Release build; five browser
regression rounds; RTL and nested intrinsic Chromium geometry controls.
Full WPT Cross is recorded separately with its Cases refresh.
Original-commit: 281a920d89
Treat comment-only and CSS-whitespace-only IntersectionObserver margin input as the empty default, and reject unitless zero and Unicode whitespace that is not CSS whitespace. The shared CSS token parser and native observer helper use the same contract. Tests cover malformed/empty comments, valid dimensions and invalid token classes.
ldm0