Describe the bug

Setting a slot prop on the svelte:element tag makes it behave in a broken way.

I'm not sure if the case I encountered is the only case where behaviour is buggy.

See the REPL for more info, but this is what made me find the bug:

1. Have a dynamic class on the svelte:element tag
2. Pass down a slot prop in the svelte:element tag
3. Update the value of the slot prop
4. The dynamic class is now gone (even though it had nothing to do with the slot pop)

Reproduction

https://svelte.dev/repl/af99dfa4e9ef45f6bce713e90af2de38?version=3.48.0

Logs

No response

System Info

System: OS: macOS 11.4 CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz Memory: 48.09 MB / 8.00 GB Shell: 5.8 - /bin/zsh Binaries: Node: 16.13.0 - /usr/local/bin/node Yarn: 1.22.10 - /usr/local/bin/yarn npm: 8.1.0 - /usr/local/bin/npm Browsers: Brave Browser: 101.1.38.119 Chrome: 102.0.5005.61 Edge: 101.0.1210.53 Firefox: 100.0 Safari: 14.1.1 npmPackages: svelte: ^3.47.0 => 3.47.0

Severity

blocking an upgrade