Type checking doesn't handle spread objects in <slot />

[rgossiaux]

Describe the bug
Not sure if this is only in strict mode, but at any rate: if you do <slot {...foo} /> and try to use the slot props with let:, you get an error: Property 'XXX' does not exist on type '{}'. Here's a tiny repl showing that this is valid Svelte, that nonetheless gives a type error if you run it through the language tools: https://svelte.dev/repl/c7041a4f46cf47fa88127ac4ec46b9b3?version=3.44.3

To Reproduce
See above.

Expected behavior
See above.

Screenshots
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System (please complete the following information):
N/A

Additional context
N/A