c.f. https://wpt.fyi/results/css/CSS2/normal-flow/crashtests/block-in-inline-ax-crash.html?run_id=5081514008641536&run_id=5202434048131072&run_id=5082008735186944&run_id=5125781984903168&run_id=5071490779709440
<rdar://problem/110839883>
This is a crash test, not a correctness test. 264701@main aligned our behavior with Firefox when it comes to timer ordering (Chrome still has the bug). As a result, it is a little surprising Firefox is passing this crash test and we're not. I looked into it and Chrome & Firefox's output is very different. Chrome runs the whole test without JS exception and produces a large output. Firefox produces a much smaller output because they throw exceptions. We have Firefox's timer ordering but don't end up throwing exception. As a result, the test ends up in an infinite loop and the WebProcess hangs. I wouldn't say this is a true regression given that this isn't a correctness and given that our new timer ordering is correct.
Exceptions thrown by Firefox: ``` Uncaught TypeError: oRange is null event_handler_ECA_DOMCharacterDataModified http://wpt.live/css/CSS2/normal-flow/crashtests/block-in-inline-ax-crash.html:50 event_handler_EC9_load http://wpt.live/css/CSS2/normal-flow/crashtests/block-in-inline-ax-crash.html:20 block-in-inline-ax-crash.html:50:25 Uncaught TypeError: oRange is null event_handler_EC9_load http://wpt.live/css/CSS2/normal-flow/crashtests/block-in-inline-ax-crash.html:31 block-in-inline-ax-crash.html:31:1 Uncaught DOMException: Node.insertBefore: The new child is an ancestor of the parent <anonymous> http://wpt.live/css/CSS2/normal-flow/crashtests/block-in-inline-ax-crash.html:127 block-in-inline-ax-crash.html:127 ```