Port SourceBrush::Brush::LogicalGradient to the new IPC serialization format.
Pull request: https://github.com/WebKit/WebKit/pull/20116
Committed 270369@main (c15041733254): <https://commits.webkit.org/270369@main> Reviewed commits have been landed. Closing PR #20116 and removing active labels.
<rdar://problem/118097026>