Remove support for 'custom-parser' in CSSProperties.json. It is now implicit for shorthands, and longhands should use the more explicit 'parser-function'.
<rdar://problem/103820303>
Pull request: https://github.com/WebKit/WebKit/pull/8137
Committed 258387@main (a0b27087082a): <https://commits.webkit.org/258387@main> Reviewed commits have been landed. Closing PR #8137 and removing active labels.