Add more tests that were written in the past years and haven't been upstreamed yet. They mostly cover laying out objects with tiny dimensions, to assure LBSE renderers these kind of documents properly. In fact it improves over the legacy engine, which had issues with these kind of documents (see discussion of test results below).
Pull request: https://github.com/WebKit/WebKit/pull/6292
<rdar://problem/102412156>
Committed 256948@main (4b037413854d): <https://commits.webkit.org/256948@main> Reviewed commits have been landed. Closing PR #6292 and removing active labels.