Use now iterator based RenderBlockFlow::computeLineAdjustmentForPagination
<rdar://problem/105676940>
Pull request: https://github.com/WebKit/WebKit/pull/10361
Committed 260543@main (3fa3e382d441): <https://commits.webkit.org/260543@main> Reviewed commits have been landed. Closing PR #10361 and removing active labels.