Index each row's cell range and row-group boundary to remove repeated
placement scans. Cache complete table measurement outputs, including
baselines, in an eight-entry LRU with layout cache invalidation.
Preserve caption minima, Flex table heights, percentage padding bases,
anonymous table behavior and the existing vertical layout path. Extend
the Chromium geometry fixtures and refresh the full WPT-cross case lists.
Validation:
- cargo fmt --all
- cargo clippy --workspace --all-targets --all-features -- -D warnings
- cargo nextest run --no-fail-fast: 18180 passed, 13 skipped
- WPT-cross all: 8779/12906 passed; table: 535/716 passed
- Table results unchanged by index/cache optimization; 28 full-run
differences checked twice per binary with no stable new regression
ldm0