Avoid unnecessary vector comparison in RenderLayerBacking::setBackingSharingLayers().
Pull request: https://github.com/WebKit/WebKit/pull/17465
Committed 267672@main (5b0a76d90281): <https://commits.webkit.org/267672@main> Reviewed commits have been landed. Closing PR #17465 and removing active labels.
<rdar://problem/115056266>