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
ldm0