`RenderLayerScrollableArea::computeScrollDimensions()` computes its dimensions by subtracting the edges of the layer’s renderBox. This could be equivalently done by directly accessing the width and height of that renderBox.
Pull request: https://github.com/WebKit/WebKit/pull/15542
Committed 265805@main (e6a64b6cddd8): <https://commits.webkit.org/265805@main> Reviewed commits have been landed. Closing PR #15542 and removing active labels.
<rdar://problem/111852761>