angular-file: BUG: `ngfDrop` directive doesn't work with IE11

Drop a file on ngfDrop zone in IE11 and it will open in browser (default IE file drop action).

Can reproduce using demo site: https://ackerapple.github.io/angular-file/

The original unforked ng2FileDrop directive still works fine with IE11 here: https://valor-software.com/ng2-file-upload/

I did a small amount of debugging - it appears the drop event is handled by ngfDrop.onDrop() but files = [] here:

let files = this.eventToFiles(event)

if(!files.length)return