Convert anonymous functions to arrow

[xjamundx]

Anytime we have an anonymous function we can convert to an arrow function

hello(function () {

});

// becomes
hello(() => {

})

[nickmccurdy]

This would be cool, but careful about the differences in scope with this and arguments. It might be enough to only run this on functions that don't use either keyword, though if someone uses this you can't be 100% sure if they're using a this in another scope or if a scope is bound to the anonymous function.