This continues #286 Changelog: - Upstream: https://github.com/servo/stylo/compare/360787fff5114f5489ffdd6b2cfd39a34e1e3ac1...7cd2a178d3c3ea1a8a88a6af211c0a0e6233c9fe - Servo fixups: https://github.com/servo/stylo/compare/e4d50e905e5081e94bdc4a553a44b221c4ad999f...d9831d464bd254e2d71e2ec58c78feaa85fb2a27 Servo PR: https://github.com/servo/servo/pull/42361
