See testcases at https://bug682780.bugzilla.mozilla.org/attachment.cgi?id=556570 and https://bug671491.bugzilla.mozilla.org/attachment.cgi?id=545914 The former involves a float; the abs pos element should be to the right of the float. The latter involves "text-align: center"; the abs pos element should have its left edge centered in the block. Presto seems to have a similar bug. Gecko and Trident seem to get this right.
Created attachment 106144 [details] Another testcase with float showing the inconsistency depending on whether the abs pos thing is first in the block
Attached test case - Chrome Canary 114 & Safari Technology Preview 166 match each other while Firefox Nightly 113 is showing 'expected result'. While following mentions: Test Case - https://bug671491.bmoattachments.org/attachment.cgi?id=545914 ^ All browsers are matching. Just wanted to share updated test result. Thanks!
Firefox produces correct rendering. This is going to progress in WebKit when bug 254394 is landed.
This is fixed now (262277@main) (IFC progression).