types(defineComponent): Support emit when using functionalComponent

[pikax]

  describe('emit', () => {
    const MyComponent: FunctionalComponent<
      { foo: number },
      { ev: (a: string) => void }
    > = (_, _2) => {}

    defineComponent(MyComponent)
  })

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	85.9 kB	32.7 kB	29.5 kB
vue.global.prod.js	132 kB	49.4 kB	44.3 kB

Usages

Name	Size	Gzip	Brotli
createApp	47.9 kB	18.9 kB	17.2 kB
createSSRApp	50.7 kB	20 kB	18.2 kB
defineCustomElement	50.3 kB	19.7 kB	18 kB
overall	61.3 kB	23.7 kB	21.6 kB