arrow function are not "bindables"

[dcharbonnier]

https://github.com/minio/minio-js/blob/master/src/main/minio.js#L282
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

> obj = {test:"from the object"}
{ test: 'from the object' }
> let arrowFunction = () => console.log(this.test);
> let regularFunction = function() {console.log(this.test)};
> let bindArrowFunction = arrowFunction.bind(obj);
> let bindRegularFunction = regularFunction.bind(obj);
> arrowFunction()
undefined
> regularFunction()
undefined
> bindArrowFunction()
undefined
> bindRegularFunction()
from the object

[krishnasrinivas]

thanks @dcharbonnier }.bind(this) must have been from previous code when it was function(){ } style, we'll fix it.

[deekoder]

Pending PR