setBackground in the webview_flutter_wkwebview is using an int? to represent the color, which, now that Color uses full doubles for r/g/b/a, like UIColor does (to support wide gamut) is lossy. For now I'm replacing the deprecated value used to set that with the equivalent toARGB(), but that's not actually the right solution.

I was going to use a simple data object since proxying UIColor seemed like overkill for this, but discovered that Proxy API doesn't allow using data classes, so I'm filing this for figuring out what the best way to handle this is.