fix: infer svg namespace correctly

[navorite]

[WIP]: closes #10025, the following cases where it would infer the namespace as html are now fixed:

• Having a comment inside the markup
• Having a {@const} tag inside the markup
• Having blocks inside the markup

Edit: I think there might be a better approach to this, as this wouldn't solve a case like this:

<text x=1 y=50>test</text>

<!-- the if/each block would make the component infer HTML namespace 
thus elements outside the if/each block are part of the HTML namespace
-->
{#if x} 
<text x=1 y=50>true</text>
{:else}
<text x=1 y=50>false</text>
{/if}

Svelte 5 rewrite

Please note that the Svelte codebase is currently being rewritten for Svelte 5. Changes should target Svelte 5, which lives on the default branch (main).

If your PR concerns Svelte 4 (including updates to svelte.dev.docs), please ensure the base branch is svelte-4 and not main.

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• Prefix your PR title with feat:, fix:, chore:, or docs:.
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

[changeset-bot]

🦋 Changeset detected

Latest commit: eb8475f

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

This PR includes changesets to release 1 package

Name	Type
svelte	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[vercel]

@navorite is attempting to deploy a commit to the Svelte Team on Vercel.

A member of the Team first needs to authorize it.

[dummdidumm]

Suggested change

	parent_node.type === 'SnippetBlock' ||
	parent_node.type === 'IfBlock' ||
	parent_node.type === 'EachBlock' ||
	parent_node.type === 'AwaitBlock')
	parent_node.type === 'SnippetBlock')

[dummdidumm]

Thank you for tackling this, but this is not quite right. We need to keep the check above as-is, and instead need to check that if we discover if/await/each blocks while traversing the nodes here, that the top level children of those are all svg elements (basically this loop needs to become recursive). Also, could you add a test case for this?

[navorite]

Yeah, I realized that is the correct approach while trying to fix it, that's why I kept it a draft. I will add a test case shortly and maybe implement this.