See https://github.com/web-platform-tests/interop/issues/575 & https://phabricator.services.mozilla.com/D190444
<rdar://problem/116803886>
It's basically moving the early return checks from https://searchfox.org/wubkat/rev/e21786e1635702a6ca7c1e30290f32e8a97fec23/Source/WebCore/style/CustomPropertyRegistry.cpp#84 to https://searchfox.org/wubkat/rev/e21786e1635702a6ca7c1e30290f32e8a97fec23/Source/WebCore/css/parser/CSSParserImpl.cpp#1028
Pull request: https://github.com/WebKit/WebKit/pull/19050
Committed 269466@main (31ae9755adc7): <https://commits.webkit.org/269466@main> Reviewed commits have been landed. Closing PR #19050 and removing active labels.