Rollup merge of #122937 - Zalathar:unbox, r=oli-obk

Unbox and unwrap the contents of `StatementKind::Coverage`

The payload of coverage statements was historically a structure with several fields, so it was boxed to avoid bloating `StatementKind`.

Now that the payload is a single relatively-small enum, we can replace `Box<Coverage>` with just `CoverageKind`.

This patch also adds a size assertion for `StatementKind`, to avoid accidentally bloating it in the future.

``@rustbot`` label +A-code-coverage

0 files changed, 0 insertions, 0 deletions