Error in IE 11

Hi there,

I have come across an error in IE 11:

`Syntax Error: node_modules/vue-js-toggle-button/src/Button.vue:40`

The issue appears to be on these lines:

`const contains = (object, title) => {
return typeof object === 'object' && object.hasOwnProperty(title)
}`

I actually use the same syntax in my own project and that doesn't give an IE 11 issue - so possibly the error is related to how this plugin is compiled?

If I can be of any other help let me know.