[1] Extensions to CSS3 Media Queries ( (2013-07-28 13:48:57 +09:00 版)) http://web.archive.org/web/20110903020848/http://www.webkit.org/specs/MediaQueriesExtensions.html

[2] Chrome で試してみましたが、値は非負の <number> みたいです。 2013-08-04T10:20:07.700Z

[3] Issue #9. Add -webkit-animation* to list of simple aliases. · whatwg/compat@eef5dde (2015-10-31 12:12:30 +09:00 版) https://github.com/whatwg/compat/commit/eef5dde8fde9bff835f757b8fdf32c03427b18f8

[4] Fixes #27. Fix -webkit-animation-direction typo. · whatwg/compat@48e278c (2016-01-17 15:33:31 +09:00 版) https://github.com/whatwg/compat/commit/48e278c27563c08fdff2a230fb41579570c8d25a