HTML: Preserve YAML front matter block

[MarcelWoerner]

Prettier is smart enough to preserve YAML front matter blocks in Markdown files, but currently strips them from HTML files, which breaks HTML sites.

The same logic that allows Prettier to ignore YAML headers in Markdown files should be applied to HTML.

Prettier pr-4392
Playground link

Input:

---
testvar: my var
anothervar: my other var
---
  
 <section>
    <div class="grid-container">
        <div class="grid-x grid-margin-x align-center">
            <div class="cell shrink text-center">
                <h5>Headline</h5>
            </div>
        </div>
    </div>
</section>

Output:

SyntaxError: Invalid left-hand side in prefix operation (1:3)
> 1 | ---
    |   ^
  2 | testvar: my var
  3 | anothervar: my other var
  4 | ---

Expected behavior:

[alexander-akait]

@MarcelWoerner we don't support HTML right now #1882

[phifa]

@evilebottnawi i was just running into the same issue. is #1882 the official issue? any plans to make this work? thanks!

[lydell]

That's the official issue.