pr-9043.md

Fix format on html with frontMatter (#9043 by @fisker)

<!-- Input -->
---
layout: foo
---

Test <a
href="https://prettier.io">abc</a>.

<!-- Prettier stable -->
TypeError: Cannot read property 'end' of undefined
  ...

<!-- Prettier master -->
---
layout: foo
---

Test <a href="https://prettier.io">abc</a>.