Functions declaring `this` as first argument should not be converted

[smartinio]

Description

Some custom userland functions that are ultimately passed back into a library are sometimes required to be methods with this declared as first arg for correct types, regardless of whether this is needed by the userland function body. One such example is fastify's app.setErrorHandler(fn) (5.1.0)

Suggested Solution

Do not convert functions where the first argument is this

Help Needed

None

[JamieMason]

Released in 3.9.1