[Flow] did not recognize object of type "PropertyDefinition"

Got this while using jscodeshift and tracked it down to this project. I was able to fix this error with this PR.

I added `PropertyDefinition` in this [PR](https://github.com/benjamn/ast-types/pull/727/files) from [there](https://github.com/facebook/flow/blob/fc180af0ab01a25cf6b64ef0d803072ff5da29a0/packages/flow-parser/test/custom_ast_types.js#L74)

@benjamn you merged #514 maybe you can have a look here too 🙏 ?

Review PR #727 and the referenced Flow file, packages/flow-parser/test/custom_ast_types.js, to understand the expected PropertyDefinition node. Verify that ast-types recognizes this node when used through jscodeshift; done means the reported error no longer occurs and the existing node definitions remain consistent.

Written by the indexing model from the issue text.