FontFaceSet queries compared family names with ASCII-only case folding, while native web-font layout used Unicode lowercasing. The same face could be missed by check/load or selected differently during layout. Share a CSS family matching key between both consumers using Unicode simple folding of UTF-16 code units, matching [Blink's font-family cache hash](https://chromium.googlesource.com/chromium/src/+/a03603fe9af6230a12f1b2fb2c18a7d003a0d937/third_party/blink/renderer/platform/wtf/text/case_folding_hash.h#50). Keep original descriptor spelling and platform/local full-name lookup intact. Register each web font only under its private source family, so Fontique cannot bypass CSS matching through a second public alias. Keep Blob identity and incremental-registration assertions by resolving the CSS alias through the document registry in those tests.
Validation: cargo fmt --all; strict all-feature workspace Clippy;
cargo nextest run --no-fail-fast (20633 tests run: 20633 passed (9 slow), 19 skipped).
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