This makes parsing less ambiguous, which is nice (we can continue to not
actually care about indentation!) and aligns nicely with `fn` for the
declaration itself.
Change-Id: Id48f064e2a1e01c5105297be355d0991b312b76d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2615
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>