We should optimize the most frequent case (non nested rule) by avoiding an unnecessary copy.
<rdar://problem/108037598>
Pull request: https://github.com/WebKit/WebKit/pull/12735
Committed 262953@main (547e70e42ef9): <https://commits.webkit.org/262953@main> Reviewed commits have been landed. Closing PR #12735 and removing active labels.
Committed 259548.651@safari-7615-branch (019aecf27efd): <https://commits.webkit.org/259548.651@safari-7615-branch> Reviewed commits have been landed. Closing PR #551 and removing active labels.