Fix bug in CSSCalcOperationNode::createHypot() found by new libcpp assertions.
<rdar://104981701>
Pull request: https://github.com/WebKit/WebKit/pull/9574
Committed 259814@main (a19262e5a43e): <https://commits.webkit.org/259814@main> Reviewed commits have been landed. Closing PR #9574 and removing active labels.