Event Modifier on keyed spread

[jackzard]

Describe the bug
when using spread lists (keyed), then lists is updated, event will be duplicate/multiplied

To Reproduce
https://svelte.dev/repl/a53e38c2ac7a4bd1bf7103454e5bfe03?version=3.19.1

[YvanDaSilva]

Just had the same issue.
A simple sort on an array used by a keyed list will result in duplication of the events.
Very annoying.

Did tested @tanhauhau fix, but it looks good.

[Conduitry]

This is fixed in 3.20.0 - https://svelte.dev/repl/a53e38c2ac7a4bd1bf7103454e5bfe03?version=3.20.0