When interacting with form controls (which triggers partial invalidations of PDF content), we trigger async tile paints, and this results in flashing.
<rdar://problem/123479307>
Pull request: https://github.com/WebKit/WebKit/pull/24984
Committed 275253@main (c6069f49ce6b): <https://commits.webkit.org/275253@main> Reviewed commits have been landed. Closing PR #24984 and removing active labels.