Speeds up Speedometer2/FlightJS by 2%.
<rdar://problem/109119378>
Pull request: https://github.com/WebKit/WebKit/pull/13660
Committed 263944@main (e1e2cbbf2d6f): <https://commits.webkit.org/263944@main> Reviewed commits have been landed. Closing PR #13660 and removing active labels.