There is a build error when CSS_BOX_DECORATION_BREAK is disabled on LineBuilder::candidateContentForLine.
Created attachment 468228 [details] Patch
Committed 269362@main (f2560fbccb1a): <https://commits.webkit.org/269362@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 468228 [details].
<rdar://problem/117018650>
Re-opening for pull request https://github.com/WebKit/WebKit/pull/19162
CSS_BOX_DECORATION_BREAK has been enabled for 10 years. Why are you building with it turned off? Can we just remove it?