Merge pull request #5392 from ampproject/fix/4604-parse-turn-unit

Patch the PHP-CSS-Parser library to correctly validate the `turn` unit

Author: westonruter

composer.json

@@ -52,6 +52,7 @@
     },
     "patches": {
       "sabberworm/php-css-parser": {
+        "Add additional validation for size unit <https://github.com/sabberworm/PHP-CSS-Parser/pull/193>": "patches/php-css-parser-pull-193.patch",
         "Validate name-start code points for identifier <https://github.com/sabberworm/PHP-CSS-Parser/pull/185>": "patches/php-css-parser-pull-185.patch",
         "Fix parsing CSS selectors which contain commas <https://github.com/westonruter/PHP-CSS-Parser/pull/1>": "patches/php-css-parser-commit-10a2501.patch"
       }