fix(gatsby-plugin-mdx): don't allow JS frontmatter by default (#35830)#35832

Merged

pieh merged 1 commit intorelease/4.15from backport-4.15-35830

Jun 2, 2022

+354-24

Commits on Jun 2, 2022

fix(gatsby-plugin-mdx): don't allow JS frontmatter by default (#35830 )
pieh
committed