Closes #5117
Closes #5119

• switch to htmlparser2
  • no need to fork
  • won't generate pseudo nodes (parse5 will)
  • should be faster
• support custom self-closing tags
• support HTML entities
• remove extra trailing newline for <template> (repro)
• distinguish empty/empty-string attributes (<tag x>/<tag x="">)
• rename --parser parse5 with --parser html
  • since we didn't officially release it, I guess we don't need to deprecate/redirect it?
• enable html since 1.15, which means it's enabled by default if you install the dev version from GitHub after this PR merged.

Prettier pr-5127
Playground link

--parser html

Input:

<Custom />

<template><div class="app"></div></template>

<X a/>

<X a=""/>

&quot;

Output:

<Custom />

<template>
  <div class="app"></div>
</template>

<X a />

<X a="" />

&quot;

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory)
• I’ve read the contributing guidelines.

@StarpTech Sorry, it seems we do not need to switch to your fork.

@StarpTech @thorn0 Thanks for your advice!