fix(compiler-dom): avoid stringify <option> with null value

[edison1105]

close #12093

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	101 kB	38.1 kB	34.3 kB
vue.global.prod.js	160 kB	58 kB	51.5 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	49 kB	18.9 kB	17.2 kB
createApp	55.6 kB	21.4 kB	19.6 kB
createSSRApp	59.6 kB	23.1 kB	21 kB
defineCustomElement	60.4 kB	23 kB	20.9 kB
overall	69.3 kB	26.5 kB	24.1 kB

[pkg-pr-new]

Open in Stackblitz

@vue/compiler-core

pnpm add https://pkg.pr.new/@vue/compiler-core@12096

@vue/compiler-dom

pnpm add https://pkg.pr.new/@vue/compiler-dom@12096

@vue/compiler-sfc

pnpm add https://pkg.pr.new/@vue/compiler-sfc@12096

@vue/reactivity

pnpm add https://pkg.pr.new/@vue/reactivity@12096

@vue/runtime-core

pnpm add https://pkg.pr.new/@vue/runtime-core@12096

@vue/compiler-ssr

pnpm add https://pkg.pr.new/@vue/compiler-ssr@12096

@vue/runtime-dom

pnpm add https://pkg.pr.new/@vue/runtime-dom@12096

@vue/server-renderer

pnpm add https://pkg.pr.new/@vue/server-renderer@12096

@vue/shared

pnpm add https://pkg.pr.new/@vue/shared@12096

vue

pnpm add https://pkg.pr.new/vue@12096

@vue/compat

pnpm add https://pkg.pr.new/@vue/compat@12096

commit: 4eba15b