feat: add support of handleEvent object listener

[7nik]

Closes #8196

The type of on:event on components is still function only, though it works with the object handler. Not sure where to fix it.

In the following case, it can be considered kind of a breaking change:

const props: HTMLAttributes = $props();
// later
props.onclick(); // will error when `onclick` is an object handler

someFnAcceptingCallback(props.onclick); // same problem

and any other place where the event handler is expected to be function only.

Also, the handler object seems to never get hoisted.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 502a772

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

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svelte	Minor

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[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@15856

[ottomated]

Is this worth adding? It seems like it's a non-zero amount of complexity and overhead for a basically useless feature, but if there's a legitimate use for handleEvent objects I suppose it could make sense to match the DOM spec

[Ocean-OS]

Is this worth adding? It seems like it's a non-zero amount of complexity and overhead for a basically useless feature, but if there's a legitimate use for handleEvent objects I suppose it could make sense to match the DOM spec

I've been using this feature for a little while and have found it quite useful. Here's the article through which I found out about it, it's pretty interesting