Allowing 'part' attributes

[megasys1968]

Is your feature request related to a problem? Please describe.

I'm developing a custom element in Svelte and when I specify 'part' attribute, I get an error on the VS Code.

Type '{ part: string; }' is not assignable to type 'HTMLProps<HTMLDivElement>'.
  Property 'part' does not exist on type 'HTMLProps<HTMLDivElement>'.

However, the compilation finished successfully and 'part' attribute works.

Describe the solution you'd like

Add 'part' property to HTMLAttributes interface, like this:

interface HTMLAttributes<T extends EventTarget> extends DOMAttributes<T> {
  ...
  part?: string;
}

When I try to apply it to svelte-jsx.d.ts, which is used by Svelte for VS Code, the error disappear.

Describe alternatives you've considered
No.

Additional context
No.

I am not a native English speaker. Sorry if my explanation is wrong.