fix: ensure mark_reactions occurs for dirty signals

[trueadm]

There was a bug in https://github.com/sveltejs/svelte/pull/12921. I've revised the logic and added a comment for it, we should only apply new heuristic for when we are setting the status to MAYBE_DIRTY.

Funnily the failing case is captured in the $state.link PR.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: e352eccbc2fa19419a1b38797e78f3d7e692bf2b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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svelte	Patch

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[dummdidumm]

@trueadm what's the status on this here? There was some concerns about readability, but given that it seems to fix #13174 (in which case we should also add a test to this PR) I'd like to get this in soon

[trueadm]

@dummdidumm I don't see how this PR can fix that issue? I'll look into it tho

[dummdidumm]

Mhm I think I was mistaken - one of the reproductions in that issue did work in the REPL of this PR, but I can't reproduce that anymore, it now fails in this one, too.

[Rich-Harris]

Is this PR still live? As mentioned the logic is somewhat unclear, and the changeset and the code don't seem to correspond to each other

[trueadm]

It was a perf opportunity. I’ve had bigger fish on my radar though so feel free to take over or close