evm_snapshot for the OVM

[platocrat]

Is your feature request related to a problem? Please describe.
Someone in our discord asked whether we have evm_snapshot implemented for the OVM.

Is this something that could be implemented in the near future?
What blockers prevent this feature from being added quickly?

[gakonst]

It cannot be implemented on l2geth because geth does not support this kind of snapshotting logic. It can be done if we used ethereumjs-vm and patched it for the OVM (we used to do that), but this is cumbersome to maintain and is not currently a priority. If anybody ends up building an OVM patch on top of the latest ethereumjs-vm, that'd be useful. Here's where we'd landed before: https://github.com/ethereum-optimism/ethereumjs-vm