Universal module definition (umd) support added

[imefisto]

Hi ! I've used your code with requirejs, so I've added UMD support.

Thank you.

[2is10]

Thanks! Could you do this without touching so many lines? With the factory function added, the IIFE is no longer needed. Seems like the file could start with this:

// github.com/2is10/selectionchange-polyfill

(function (root, factory) {
    if (typeof define === "function" && define.amd) {
        define([], factory);
    } else if (typeof exports === "object") {
        module.exports = factory();
    } else {
        root.selectionchange = factory();
    }
}(this, function (undefined) {
  var MAC = /^Mac/.test(navigator.platform);
  ...

...and nothing else would need to change except removing this from the bottom:

if (typeof module !== 'undefined') {
  // CommonJS/Node compatibility.
  module.exports = selectionchange;
}

[2is10]

Also, please stick with the indentation level this file is already using: 2 spaces. Thanks.

P.S. Good news, Firefox 52 (scheduled for release March 7) has the selection events API.