Fix ASSERT crash in masonry-grid-template-columns-computed-withcontent.html
Pull request: https://github.com/WebKit/WebKit/pull/8422
Committed 258700@main (929973a6b81a): <https://commits.webkit.org/258700@main> Reviewed commits have been landed. Closing PR #8422 and removing active labels.
<rdar://problem/104058806>