The test is failing in Blink and WebKit:
Check the following www-style thread for reference:
Created attachment 460358 [details]
Safari 15.5 matches Chrome but differs from Firefox
I am able to reproduce this bug in Safari 15.5 on macOS 12.4 using following link:
Link - https://test.csswg.org/shepherd/repository/52ee0d2e5ed669cafed3a7a50d3936e6205cac9b/css21/selectors/first-line-selector-011.xht
Please refer to attached screenshot for other browsers. Chrome Canary 105 follows Safari 15.5, while Firefox shows expected result and render the output in "GREEN" text. Thanks!