Summary:
Now that [exact_empty_objects has been enabled](https://fb.workplace.com/groups/flowlang/posts/1092665251339137), we can codemod `{...null}` to `{}` - they are now equivalent.
1) Run my one-off jscodeshift codemod
2) `scripts/flow/tool update-suppressions .` (as some suppressions move around due to the change)
drop-conflicts
Reviewed By: bradzacher
Differential Revision: D37834078
fbshipit-source-id: 6bf4913910e5597e5dd9d5161cd35deece6a7581