Per https://drafts.fxtf.org/filter-effects/#interpolation-of-filters, we should use a discrete animation when either of the animated filter value contains a url() function.
Pull request: https://github.com/WebKit/WebKit/pull/6754
Committed 256970@main (582bdb346c12): <https://commits.webkit.org/256970@main> Reviewed commits have been landed. Closing PR #6754 and removing active labels.
<rdar://problem/102626239>