CSSCalcOperationNode::evaluateOperator & CalcExpressionOperation::evaluate are almost identical.
<rdar://problem/111962034>
Pull request: https://github.com/WebKit/WebKit/pull/15669
Pull request: https://github.com/WebKit/WebKit/pull/15670
Committed 265888@main (4ea2d50a5f28): <https://commits.webkit.org/265888@main> Reviewed commits have been landed. Closing PR #15670 and removing active labels.